DIVE LOG AUSTRALASIA FEB 2026

FEBRUARY 2026 | No 416 digi tal

AUSTRALASIA

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FREE UNDERWATER PHOTOGRAPHY COURSE CH 4 PHOTOGRAPHING WRECKS MIKE SCOTLAND

SPOTLIGHT ON WRECKS FREE DIVING DIVING MELBOURNE VADIM BELAKHOV

HERON ISLAND DIVE FESTIVAL ORGANISED BY DIVE LOG FUVAHMULA TIGER SHARKS KEN HOPPEN

new

PURSUE PERFECTION HYDROS PRO 2 BCD

heavy-duty, quick-dry bladder

enhanced control

advanced monorail weight system

scubapro.com

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MODULAR FIN SYSTEM BY SCUBAPRO The ability to change anything, changes everything. Take max power to the next level with SCUBAPRO’s Modular Fin System. Choose from the Seawing Supernova or S-Tek blades in multiple colors and a full foot or boot-fit foot pocket to assemble your perfect fin. SCUBAPRO’s Modular Fin System (MFS) goes beyond personalization. This high performing fin offers a range of interchangeable components allowing you to optimize your fins for your various dive conditions and add personal style and color. It starts with foot pocket selection, open heel to wear with boots and full foot to dive barefoot. Next, choose your blades. The Seawing Supernova offers maximum speed, power, and maneuverability in a variety of colors, while the S-TEK blade is designed for precise alternate kick control. The two-piece design saves space in your bag. SCUBAPRO’s Seawing Supernova Blade represents the next generation of powerful SCUBAPRO fins. Winner of the prestigious, internationally-recognized Red Dot Award for product design, the Seawing Supernova is a step up from the Seawing Nova in performance, construction, fit and versatility. The proven Pivot Control Technology (PCT) works in tandem with the unique Auto-Adjust central panel to always provide the optimal angle of attack for the blade.

The PCT hinges pre-set the blade in the 40º to 50º range that is ideal for converting kicks into forward motion. The flexible Auto-Adjust central panel then fine-tunes the angle of attack according to the strength of kick by counterpivoting, providing a milder angle of attack for comfort when kicking gently, a more aggressive angle of attack when kicking at full strength, and anything in between. When it comes to frog and alternate kicks, the new twin-tip winglets increase control and markedly improve maneuverability. Made of premium Monprene for maximum durability, the Seawing Supernova’s innovative two piece design, with blade and foot pocket molded separately, makes transport easy. The Seawing Supernova Blade is the go-to blade for avid recreational and professional divers seeking maximum speed, power and control in all diving conditions. Foot pocket sold separately. Complete open heel fins in Black and white: AUD$391.00 Complete S-tek Fin Open Heel: AUS$404.00 Full Foot Pockets in Black and White: AUS$85.00 Optional color Blades (Pink, Blue, Yellow, Turquoise) : 170.00 AUS$ Fo more info, go to https://scubapro.johnsonoutdoors.com/us/shop/fins/modular

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MVOCEANIA/J' Our newest dive liveaboard operating out of Walindi Resort since 2019. Diving Bismarck Sea and Milne Bay

rest5ft

mv

LIVEABOARD MV FeBrina has been operating from Walindi Resort since 1991. Bismarck Sea, Including New Britain & Kavieng

Walindi Plantation Resort celebrates 40 years of operation. Diving Kimbe Bay Reefs

DICHOTOMY OF THE DEEP: a message of hope. The health of the ocean is harmed by overfishing to such a degree that it should be front page news. The endless take, take, take from the ocean has brutalized marine life in most seas across the entire planet for centuries. The total collapse of fisheries all across the globe leaves us in a perilous situation that, unfortunately far too many persons are unaware of. The poor state of the oceans and the complete decimation of fisheries around Great Britain in the 19 th Century, South America in the 20 th C. and now the Antarctic ocean continues. Governments are weak and fail to enforce weak laws made to provide sustainable fisheries into the future. I like to imagine Spacemen overseeing the human race from a nearby galaxies that are amazed that the Blue Planet, this paradise oasis called Earth, has been vandalised to such a degree that one day it could spell disaster for the human race. I hope that they will step in before it is too late. We all know that Hollywood frequently makes movies about the imminent destruction of our planet with a hero saviour. Well, the saviour is Science and it is us. Science is knowledge. It is fact gleaned by research, observation. Knowledge is the greatest growth industry of all. Think of the progress mankind has made in the last two centuries. E.G, millions of the most brilliant minds throughout history have developed solutions to killer medical issues. These include antiseptics, antibiotics, Vaccines, surgical intervention, pain killers and many thousands of other miracles of modern medicine. When Europeans colonized Africa, they introduced modern medicine. They set about curing many deadly afflictions that shortened the lives of Africans since the dawn of time. This positive contribution of colonisation is never mentioned by the media… how modern medicine improved and extended the lives of most humans everywhere across the entire globe. In the 21 st Century, untold numbers of research scientists are studying the ocean and learning more and more about each and every organism. Sadly, the enormous boom in knowledge is always trumped by big business and Mass Media control and now A.I. Corporations want to “Dig Baby, dig” to make a dollar. They won’t stop until we the people make them stop. As the song says, “When will they ever learn?” As I always talk about, take a thousand-year view of life on earth to see the deforestation and over-fishing. Take a hundred-year view of corporations. Their power grew ten times in the last 70 years. Many are bigger than countries and they strip assets from the masses and have unlimited expansion of their empires. They even disregard laws. A.I. completes the total dominance of many corporations over the wallets of every human and they will grow further and have grown until the almost totally powerless men and women in the street, that’s us, wake up and see that they have lost nearly all of the freedoms. This is portrayed brilliantly in the movie “V for Vendetta”. when corporate media has total mind control of the masses. People fight back and take back their lives. We can save the Oceans. It is simple. You and I can take back the power. You and I are the master of the future as long as we do something about it. Create Marine Parks and police them. Build fish hatcheries and restock the ocean. Get governments to make corporations behave with more ethics. E.g. with whaling. Educate people to the benefits of healthy seas. It really is all so easy to do! OUR COVER PHOTO This coloutful photo is a diver in the Kingposts of the Sankisan Maru in Chuuk Lagoon by Mike Scotland

In short, follow the Great Barrier Reef’s (GBR) example. It has 36% protected in Green zones and Research only zones. Marine life can breed. It is a sanctuary, a safe haven. Corals rebuild and the entire health of the ocean recovers. Southern Australia has a free for all with such a tiny miserable area of marine sanctuaries, token enforcing of regulations that it is equal to no protection. Governments need to talk to people. Everyone wants peace, prosperity and a healthy planet. The Governments need to show a strong commitment to saving the ocean. At present, politicians are afraid of being voted out by the people who over exploit the fish. Illegal whaling ships reprovision in Tasmania so they can go and break the whaling policy that Australia is supposed to support? Where we are heading now. I dived with a group of divers from Buffalo, New York. They mentioned that they wanted to see big fish at a popular resort in the South Pacific. They lamented about the disappointing lack if big stuff. It is true. The biggest fish I saw was a Sweetlip. NO Coral Trout or big pelagics, rare sharks, almost no turtles. The GBR on the other hand has lots of BIG STUFF. Fifty years of protection has seen fish populations rebuild, coral reefs rebound. More importantly, the diving is good. Here is a simple message. The GBR will take its place as one of the top dive destinations in the world! Please explain, I hear you say. The protection and enforcement of marine protected areas restores the health of the reef. Very few countries across the globe have anywhere near the same level of protection. When you dive there, you may the lack of fish and the empty seas. It is a sad sight. I have dived in dozens of South Pacific hot spots and on 54 expeditions to the Great Barrier Reef. If anyone has the big picture, it is people like me. My observation, these days, GBR is one leader in the pack re better diving. So, I am organizing the Heron Island Dive Festival in 2026. June 20 to 27. The purpose is to celebrate the excellent state of the reefs, the wonderful marine life and loads of BIG STUFF as to share the good news. Last year in January, I dived from Agnes Waters. The state of the southern reef impressed me and we had some of the best dives I have had on the GBR. One dive, I saw five species of sharks. So, I visited Heron Island in August. Guess what? Incredible fish life, healthy corals, so many Turtles, sharks, big Rays and big stuff. Great diving. Better still, highly trained dive crew with a friendly attitude. NO dive Nazis here! Just safety conscious, well run diving from modern boats with all the mod cons. If you are like me and have done well over seven thousand dives, you definitely do not get treated like an OWD beginner. The Feb issue of Dive Log Australasia presents another superb blockbuster of diving entertainment. This issue features photography of wrecks, Nudibranch defenses, diving with Tiger sharks, and details about one of the diving the events of the year, the upcoming Heron Island Dive Festival. This is being resurrected by Dive Log to celebrate the wonderful diving on the Great Barrier Reef.

Happy diving. Mike

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CONTENTS

FEBRUARY 2026

digital

N o. 416 NEXT ISSUE DEADLINE : Issue 417 March 2026 Advert bookings 12th Mar Artwork due 15th Mar Editorial material : 12th Mar

015 WAKATOBI A Cornucopia of Colour Mike Scotland 020 NUDINOTES by David Mullins 023 Night Freediving at Port Phillip by Vadim Belakhov 032 CH 4 Shipwreck photography Mike Scotland. 042 HERON ISLAND DIVE FESTIVAL Speakers Promo 054 MIDE MALAYSIA DIVE EXPO 047 TUFI A dream World by Armin Merkel 056 SPOTLIGHT SHIPWRECK PHOTOGRPAHY 060 FUVAHMULAH TIGER SHARKS by Ken Hoppen 066 ADEX Dive Expo David Strike 070 WRECK PHOTOGRAPHY TRUK by Mike Scotland 085 PARTING SHOTS. Feature articles

EDITOR Mike Scotland mike@divelog.net.au Editor/Designer Mike Scotland divelog@divelog.net.au PUBLISHER mike@divelog.net.au ADVERTISING mike@divelog.net.au MENTOR Barry Andrewartha barryandrewartha@outlook.com

Mike’s Contact details: Tel: + 61 0415158168 mike@divelog.net.au www.divelog.net.au Editorial and photographic contribution guidelines: divelog@divelog.net.au The views expressed by contributors are not necessarily those of the publishers or its editors. REPRODUCTION OF CONTENTS No part of the contents of this publication may be reproduced without the prior written consent of the publisher. All images are copyrighted by the authors and photographers.

Regulars

43 Max Gleeson Wrecks 45 Elliot Peters Master Reef Guide 53 Spotlight by WRECKS 58 - DAN News 68 - In Deep - Simon Pridmore 79 - Underwater photo magazine 81 - Paul Watson Pirate book review 89 - Nigel Marsh MAMMALS book 90 Dive Boat Directory -

07 - Mike Ball Expeditions 03 ScubaPro’s Modular Fin System 12 PNG Resort Listings 18 Historical Diving First Decompression Gauges by Des Williams 20 NudiNotes Behaviour David Mullins 29 Shark Feeding by Kevin Deacon 30 Counter Strike -David Strike 42 HERON ISLAND DIVE FESTIVAL

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View from the Bridge Trevor Jackson - Spoilsport Skipper www.mikeball.com/blog Great Barrier Reef on the January

PHOTOS FROM NOVEMBER/DECEMBER

Gigantus Gorgonia – A Living Legend of the Coral Sea By Captain Trevor Jackson

You can scroll through a thousand Google images and not find its equal. I know this because I’ve just done it. The day after the trip ended, for hours, trying to find the equal of the aptly nicknamed Gigantus Gorgonia - a spectacular soft coral assembly, 42 metres down, way, way out in the Coral Sea. Exactly five years ago to this day, Trip Director Kerrin Jones and I measured this whopper at an astounding 5.25 metres across. There wasn’t a tape measure on board long enough to do it in one hit, so we had to take two down with us. This week, we were expecting a different result and we got one. But let me start at the beginning. Gigantus Gorgonia is at Flinders Reef, about 130 miles north-east of Townsville. Beautiful and remote, it rises out of a thousand metres of water to just break the surface at high tide. It’s a spectacular destination that was damaged by coral bleaching about ten years ago. Our main mission this week was to see how the recovery was progressing to assess whether the area had regained the coral and fish vibrancy that once made it a world-class destination. Five years ago, things were improving nicely. This time, the reef delivered in spades. The corals and marine life are back with a vengeance. For more reasons than I can count, Flinders Reef has returned to the big leagues. For three days, we explored, mapped, and documented both old and new sites. Our final day took us to the southern section of the reef and a chance to check the growth on that famous fan. New Trip Director Shona Whittaker and I geared up and located the two tape measures, eager to see how much Gigantus had grown in the past five years. The visibility? 50 metres. So nothing had changed there. As we reached the fan, Shona pulled out the first tape. I ran it across the face of Gigantus, but as she reached for the second, I waved her off. I didn’t need it. The fan had “shrunk”. It now measured just five metres across. An hour later, back on deck, our photos revealed the truth. The apparent shrinkage was due to mechanical damage—something had broken a section away. Perhaps a large cod had been using the fan as camouflage and dislodged part of it. We’ll never know. Our disappointment was short-lived. One dive later, after drifting along a nearby wall, divers came back aboard buzzing with excitement. “There’s another fan… a bigger one!” I quietly placed the tape measures into a bucket of fresh water to rinse them off. I had a feeling we might be needing them again… soon.

1st. Alison Smith

2nd. Julia Jones

3rd. Kevin Lee

Coral Sea & Great Barrier Reef! The Best Diving on the Dive with giant potato cod, explore deep walls, witness shark action at Osprey Reef.

New Special Expeditions! Check out our website for details.

Ribbon Reefs Suited to both Divers and Snorkelers.

Join our 12 March 2026 Yongala & Coral Sea Expedition and dive the legendary walls and giant sea fans of Flinders Reef.

www.mikeball.com T: +61 7 4053 0500 E: resv@mikeball.com #spoilsportlive #mikeballdive

Check out Special Expeditions on Spoilsport. www.mikeball.com/availability

“Th e r ee f s y s t e m s h e r e a r e so m e o f th e m os t pri s tin e I h a v e see n a nywh e r e in my d iv e tr a v e l s a r ou n d th e g l o b e , a n d W a k a t o bi r eso rt a n d liv ea b oa r d a r e se c o n d t o n o n e . Th e d iv e r s ity o f s p e ci es h e r e i s brilli a nt if y ou l o v e ph o t og r a phy.” ~ Sim o n B o w e n

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Up to one third of diving deaths are due to heart conditions, mainly in divers aged 45 or more.

Many of these divers were unaware of any problem.

Diving includes many stresses on the heart, including: immersion itself, exertion, breathing restriction, and gas changes in the body, among others. PREVENTION: Have your heart health checked by a diving doctor at age 45, or earlier if unwell.

Photo by Dave Bryant

Don’t dive if feeling unwell.

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The Australasian Diving Safety Foundation

The Australasian Diving Safety Foundation (ADSF) is an Australian-based Health Promotion Charity. The main aim of the Foundation is to reduce diving-related illnesses and deaths.

The ADSF supports its aims predominantly by undertaking research, providing education on diving safety, and offering grants for relevant research, diving safety promotions, dive medical training, oxygen equipment and AEDs. Funds have been allocated to support up to AUD$250,000 per year for appropriate research projects. In addition, the ADSF offers grants of up to AUD$25,000 to fund safety- related projects within the diving industry . Full details of these grants, as well as applications are available at http://adsf.org.au.

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PACIFIC OCEAN

• Diving is possible all year round with the optimal season typically from mid April to mid June, and mid September to mid December.

KAVIENG

NEW IRELAND

MANUS ISLAND

VANIMO

BISMARCK SEA

• Water temperature from 26º along the edge of the Coral Sea and up to 31ºC in the Bismarck Sea. • Visibility ranges from 50 to 150 ft • PNG has a hyperbaric chamber maintained to international standards • The use of permanent environmental moorings ensures minimal anchor damage to reefs. • Weekly flights to Port Moresby from Singapore, Hong Kong, Tokyo, Manila, Kuala Lumpur, Honiara, Nadi. Daily flights from Cairns, Brisbane, Sydney. • For the best dive and air package pre-book your complete tour with a recognised PNG dive travel specialist.

RABAUL

WEWAK

KIMBE BAY NEW BRITAIN

MADANG

TARI

HOSKINS

MT HAGEN

GOROKA

PAPUA NEW GUINEA

BOUGAINVILLE ISLAND

LAE

SOLOMON SEA

GULF OF PAPUA

TUFI

PORT MORESBY

MILNE BAY

ALOTAU

www.walindiresort.com

www.lissenung.com “Instruction, gear rental, 8 rooms (6 with ensuite, 2 with semi ensuite), free WiFi, full resort facilities. A visit at Lissenung Island Resort is truly exclusive! info@lissenung.com

Instruction, gear rental, Nitrox, 12 bungalows, 8 plantation house rooms, all ensuites, internet, pool, full resort facilities, English. Voted the 'Best diving from a resort anywhere in the world', Walindi comprises fern-draped bungalows set in tropical rainforest gardens on the shores of Kimbe Bay.

resort@walindifebrina.com

MV OCEANIA LIVEABOARD www.mvoceania.com

www.mvfebrina.com

Gear Rental, Nitrox, 10-12 passengers, English MV FeBrina cruises from Walindi Resort, diving Kimbe Bay, Witu Islands, Fathers Reefs, Rabaul and New Hanover. febrina@walindifebrina.com

Gear Rental, Nitrox, 16 passengers, English

MV Oceania is the most recent liveaboard addition to Kimbe Bay. A 27 metre catamaran, Oceania began operation in 2019 with itineraries including Kimbe Bay, Witu Islands and Fathers Reefs as well as further afield at select times of year. reservations@mvoceania.com

Image credit David Doubilet

LOLOATA ISLAND RESORT www.loloataislandresort.com

DIVE KOKOPO & WATER ADVENTURES www.facebook.com/kokopodiveandwateradventures

Luxury Island Resort with 68 - rooms/villas, two restaurants and bar, a swimming pool, recreational beach, fully equipped dive shop, spa and conference centre. Importantly, it sits on the edge of the Papuan Barrier Reef and 29 dive sites around the island where experienced divers can explore its reefs, spectacular sea life and shipwrecks.

Instruction, gear rental, WW2 wrecks, wall dives, reef dives, muck dives, shark dives. Full resort facilities, land & marine tours, wifi, pool. At Kokopo Beach Bungalow Resort with tropical bungalows in the heart of Kokopo-Rabaul with private beachfront. diving@kbb.com.pg

There are also excellent snorkelling sites. Loloata’s PADI-certified dive and activities centre is opened now, so learning to dive is also now an option. t: +675 7108 8000 / 7914 3966 e : gm@loloata.com

NIUGINI DIVE ADVENTURES www.niuginidiveadventures.com

TUFI RESORT www.tufiresort.com

Discover Tufi in a boutique resort with 180 degree panoramic views over the sea and the only fjords in PNG. Experience diving in a secluded paradise with abundant sea life, coral reefs and wrecks. The warm crystal clear waters of Tufi are a divers paradise. Gear rental, water activities, village stays, cultural and land tours. 24 air conditioned ensuite guest rooms, pool, full resort facilities. reservations@tufiresort.com Fly across mainland Papua New Guinea to remote and magical Karawari Lodge. The lodge overlooks the Karawari River whose waters flow towards the Sepik River. Stilted villages line the edges of the waterways. Dugout canoes glide by. Lodge guides introduce guests to the complex and mysterious tribal culture. Conversations with villagers are fascinating. Photo opportunities abound.

The only dive company established within ‘beautiful Madang’; the PADI certified facility, NDA is one of the most experienced dive operators in Papua New Guinea. NDA offers resort courses taught by our team of multi-lingual, PADI certified instructors and dive masters. The crystal clear waters surrounding Madang offer some of the world’s best diving

experiences for divers to discover. Most dive sites are only 5-10mins away! Underwater peaks climbing from 600m to 4m and sheltered lagoons where old wrecks, dating back to World War II, are waiting to be explored... Contact info: nda@madangresort.com

KARAWARI LODGE www.pngtours.com

TAWALI RESORT www.tawali.com

Instruction, gear rental, Nitrox, 22 ensuite rooms, Broadband, full resort facilities.Where it all started, discover the dive sites that place PNG into the world class map of scuba diving. Situated on a limestone bluff backed by densely rain

forested hills overlooking the clear and protected water of Milne Bay, Tawali offers travellers a unique location to dive, relax and enjoy the unspoiled wonders of this magnificent part of the world. reservations@tawali.com

service@pngtours.com

AMBUA LODGE www.pngtours.com

RONDON RIDGE www.pngtours.com

Explore mainland Papua New Guinea based from eco-friendly Ambua Lodge. The lodge is nestled in the highlands, overlooking the magnificent Tari Valley, home of the famous Huli Wigmen. Visit their traditional lands and learn about their fascinating culture. Follow walking trails through mid-montane forest, over traditional vine bridges and along clear mountain streams to secluded waterfalls. Watch for Birds of Paradise.

In the mountains of mainland Papua New Guinea, above the town of Mount Hagen, sits Rondon Ridge. Rising mists enhance the lodge’s panoramic views of the historic valley below. Orchids thrive here. Hours of walking trails offer opportunities to spot exotic birds, including Birds of Paradise. Lodge

guides share the history and traditions of the Melpa people. Rondon Ridge is conveniently accessible on scheduled flights between Port Moresby and Mount Hagen. service@pngtours.com

service@pngtours.com

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CORNUCOPIA OF COLOUR at WAKATOBI.

This pretty wrasse is likely to be a close relative of the Solor Wrasse, Cirrhilabrus solorensis.

W akatobi’s vertical coral gardens are rich and full of life. The diving is awesome. Every now and again, you encounter a coral grotto or overhang totally filled with soft corals, fan corals and brightly coloured sponges. Many of these corals are home to all kinds of fish and creatures. As you glide along the walls and reefs, you see many new coral formations that were not familiar. In addition, many sea caves and overhangs are home to prolific marine life.

One thousand and one colourful Coral gardens

Local branching corals unlike anything I have seen

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Deep inside a dark coral cave lies a lurking Lionfish

Ornate Butterfly fish

Some of the dive sites such as Namo Bula Bula have sandy patches at the base. Often, you can find Jawfish peering out of their rubbley jubblewy burrows Flagtail Blanquillos slither through the water keeping just out of range for your camera. Shrimp Gobies watch alertly as you approach. It is always fun to watch the untiring efforts of the Alpheid shrimp toiling away at the housekeeping whilst that vigilant Goby stands guard. I spotted a magnificent Wrasse similar to a Melanesian Wrasse. Its bright red eyes watching intently as it flashed a danger warning to the rest of the school. Down the slopes of the walls Ornate Butterfly fish swim in formation with military stealth. They move forward one by one whilst the other watches for danger. Butterfly fish constantly signal to each other that it is safe to proceed in a manner that reminds me of soldiers going from door to door in urban combat missions. Drifting amongst these colourful reefs is a wonderful experience. For more information, go to www.wakatobi.com.

There are more than forty dive sites around Wakatobi that are classified as day dives.. I explored about twenty of these dive sites, some of which I dived twice. Each dive site has a description and suitability for each various weather conditions. For example, Black Forest. Black Forest has a shallow reef connected to a deep wall by a coral slope. Overhangs and canyons make for excellent critter hunting. The steep sides of the deep wall has a forest of Black Coral Trees down in the depths that entice more experienced divers. Black Forest is a dive that is exposed to North Westerly winds so it is reserved for days when the wind is from the East or South. Allegra’s Wall features spikey Tube Sponges and Orange cup corals. There are many overhangs and coral caves filled with crevices and cracks in its walls. These coral cracks are home to many species of fish, crustaceans, flat worms, Soldier fish and Scorpionfish. Allegra’s Wall is diveable safely in all conditions except for when there is a strong Westerly wind.

A colourful cornucopia of corals

Coral gardens hide insatiable and deadly killers

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Above: Three types of Fan Coral, several types of sponges combine together to delievr this technicolour vision. Below left: Massive Table Top Corals provide shelter for soft coral gardens and Feather Stars as well as lots of marine creatures. Below Right: Beautiful deep mauve Soft Coral

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S o, where and when did the first incarnation of the modern dive computer come onto the market? It was probably earlier than you think, and a great deal of trust by divers was placed in those early analog instruments! Read on ... In 1960, Italian engineer Carlo Alinari presented his DeCompression Processor (DCP) at the CMAS General Assembly in Barcelona. It was the first analog dive computer. It was developed in collaboration with engineer Victor Aldo De Sanctis, a pioneer in the field of diving photography and videography, with whom he founded the company SOS-Strumenti Ottici Subacquei (Optical Diving Instruments) in Turin in the late 1950s. At the beginning, they launched the first depth gauges in an oil bath, the only automatic instrument for decompression calculation available at the time. The simple and reliable device was technically based on a pneumatic principle that simulated the saturation and desaturation of tissue in the human body in 120 minutes and indicated no decompression times or eventual decompression stops at depths of 3-6-9-12-15 meters. The DCPs had a plastic or stainless steel case and were manufactured up until 1990, when they were replaced by more advanced digital computers. Nowadays, the early principle may be considered primitive, but for the time it was a real revolution; it became popular with divers all over the world. Inevitably, the material used and some manufacturing defects caused some ‘variability’ in the results displayed, especially on repetitive dives; in some cases, it was referred to as the “Bend-O-Meter”. However, some of the misreadings were not due to malfunctions, but to diver’s bad habits or operation error . To understand the operation of the early instrument, whose case was made of stainless steel in 1964, we must imagine THE ANALOG SOS DECOMPRESSION GAUGES by Des Williams

it on the wrist of a diver during his descent. The ambient pressure inside a flexible bulb within the instrument rises, according to Boyle’s Law, so the excess air inside it is forced through a ceramic filter that simulates the nitrogen uptake and release of a medium human tissue, thus pressurized into a small constant volume chamber. This pressure increase inside the chamber controls a Bourdon tube pressure gauge that, through a mechanism, indicates the depth remaining above which the diver can still safely ascend. In reality, when the diver begins his ascent, the pressure in the constant volume chamber becomes greater than the external pressure; therefore, the gas flow reverses, causing a descending movement of the pointer on the Bourdon tube. The mechanism now indicates the minimum effective depth to which the diver must ascend until the indicator no longer gives the OK to ascend further, or to reach a lower deco stop. This decompression gauge, in its different versions (and thanks to the recognition of this principle) was also marketed by several other well-known diving equipment companies, such as Beuchat , Spirosub , Dacor , CressiSub , Mares , Scubapro , Technisub and others. The Four-Web DCM 4 Decompression Gauge: In 1974, SOS launched the DCM4 with four tissues, based on the DCP principle, simulating the nitrogen uptake and release of four tissues instead of one. Its four elements corresponding to tissues with saturation times from 10 to 40 minutes. Each element had an adjustment knob allowing the diver to enter specific values into the calculation, such as water temperature and dive interval times. During ascent, the diver stops at the first deco stops when the conductive fabric index enters the red zone; when the ‘OK to ascent’ is present the diver can continue his ascent and stop at the next deeper of the four depths as indicated. When all indices leave the red area, the diver may ascend to the surface. The SOS DCK Measurement Device: Released in 1975,

SOS DCS Model Deco Gauge

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this device had a clearer and easier to read display. The diver read decompression data from a moving yellow line on a grey background against red stripes indicating stops from 15 to 3 meters. The operation was very simple and once at the surface, the DCK also indicated the residual nitrogen levels in the diver’s body for the subsequent decompression procedure. DCS and DCS/Dt2 Gauges: Released between 1977 1979, the DCS was a modern analog decompression gauge with a stainless-steel case and capillary depth gauge to 60M. Ambient pressure was transmitted through a liquid transducer. The DCS was supplied with a pressure resistant case to transport it during flights to maintain its correct calibration. The Dt2 model was connected by a high-pressure hose, coupled to the regulator HP port. The gauge thus indicated the diver’s minimum air required for the necessary deco stops, via an integrated analog pressure gauge. In 1980 the SOS DCR-Manometer was the last of the SOS decompression gauges, which displayed values based on the US Navy tables and was designed for repetitive and unusual exposures with deco stops extended to 18 & 21M. However, the most popular SOS deco gauges were the DCP in both plastic and stainless-steel cases. If you would like more information about diving pioneers, contact the Historical Diving Society Australia-Pacific by email at: info@historicaldivingsociety.com.au or visit our website www.historicaldivingsociety.com.au https://m.facebook.com/groups/120950924589540/

References: Andre Campedelli HDS Italy & Lothar Seveke HDS Germany

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STAYIN ALIVE THE DEFENCES OF SEA SLUGS - Part 6 Passive Defences continued

Chemical Defences The employment of chemical compounds by sea slugs as a defensive means is integral in both passive and reactive methods. It could be considered the single most important means of self protection in dorid nudibranchs and is believed to be utilized, in one form or another, by all sea slug taxons, often in conjunction with other methods, in varying degrees of complexity.

The sea is a soup of chemicals, so sea slugs live in an environment that revolves around chemical compounds for two-way communication – incoming and outgoing – for the functioning of feeding, protection and reproduction. We only have to look at the major sensory organ of sea slugs, the rhinophores or their equivalents, designed to detect chemical cues in their fluid environment, at a distance from their release location, to appreciate

Clockwise from upper left: Sponges, ascidians, bryozoans and algae - these are the major food sources of the dorids, sacoglossans and sea hares. All of these food sources contain secondary metabolites or antifeedants to prevent predation or grazing. Sea slugs have evolved ways and means to overcome, neutralise or to even repurpose those toxic substances, often species specific. DIVE LOG Australasia #416 February ‘26 20 www.divelog.net.au

how important chemicals are in their navigation of life. Many animals and plants that form the diet of sea slugs possess anti-feedant chemicals (secondary metabolites) in their tissues as a deterrent to predation. For the sea slugs to be able to consume food that contains these anti-feedants, without consequence, is certainly advantageous, as it provides access to a broader diet and there would be fewer competitors for the same resource. However, to take them up and repurpose them for self-defense lifts the capability to a whole other level. Source These defensive chemicals are transferred from the dietary intake of sea slugs to special storage formations, often referred to as mantle dermal glands , or they might be modified or even biosynthesized de novo and stored similarly, as it has been ascertained that those particular types are

not found and ingested through their diet. The method by which the specific defensive dietary chemicals are selected, separated and transported from the ingested material is currently unknown. As mentioned, many types of marine fauna contain what are referred to as anti-feedants or secondary metabolites – organic compounds that are produced but are not necessary for the normal functioning of the organism. Sponges, the diet of many of the dorid nudibranchs, are an excellent example. Sponges contain some of the most toxic chemical compounds to be found in nature. Some sponges should not even be handled without protective gloves. There are thought to be four sources of these compounds in a sponge – those produced by the sponge itself by its own metabolism, those produced by the microbes or bacteria hosted by the sponge (the number of bacterial cells in some sponges is calculated to be higher than their own cell count), those produced by the association

The spongivorous chromodorids predate upon a variety of sponges - some broadly, others quite specific. Clockwise from upper left: Goniobranchus splendidus is known to feed upon at least five species across the Darwinellidae family; Cadlinella ornatissima shows a marked level of non- specialisation by feeding across several sponge families; Goniobranchus collingwoodi on the other hand is restricted to the Dictyodendrilla genus; Goniobranchus fidelis, based on current records, appears to be restricted to Chelonaplysilla violacea. DIVE LOG Australasia #416 February ‘26 21 www.divelog.net.au

between the host sponge and its symbionts and those pre-existing that might just arrive via the huge amounts of seawater that sponges are continually filtering. All these toxins and anti-feedants help protect this most simple of animals, the sponge, from a great deal of predation, apart from those animals that have evolved to process the toxic chemicals such as certain species of dorid nudibranchs, some fish and some turtles. Different species of these spongivore nudibranchs have different diets, that is, they only predate on a certain family or genus or even just a single species of sponge. The sponge they eat can depend on the toxic chemicals they have evolved to be able to process. Some nudibranchs that consume

bryozoans, soft corals and ascidians are also known to repurpose the toxic chemicals found within that prey as too, do sacoglossans, sea hares and the herbivorous headshield slugs from their algae diet. Symbiotic bacteria and cyanobacteria, often associated with their food, are also a source of antifeedant compounds. Reference: Rudman, W.B. & Bergquist, P.R. (2007) A review of feeding specificity in the sponge-feeding Chromodorididae (Nudibranchia: Mollusca), Molluscan Research 27(2): 60-88. Next issue: Defensive Glands - Types, Contents and Locations

The Darwinellidae sponge species Chelonaplysilla violacea appears most favoured among certain Goniobranchus . There is a group possessing purple colouration under the anterior mantle and six of these feed upon that sponge. They include these four, Clockwise from upper left: Goniobranchus geometricus; Goniobranchus hintuanenesis; Goniobranchus leopardus; Goniobranchus coi.

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Night Freediving in Port Phillip Bay: Mating Southern Dumpling Squid

text and photos by Vadim Belakhov

Challenging and Teeming with Life Night dives are very special to me. I try to hit the water at least once a week all year round, usually doing night dives on weekdays after

work. There is so much to discover in the shallows of the Bay, especially after sunset. The water around you is pitch black, and you can only see as far as your torch allows, so I mostly concentrate on small and macro subjects.

My favourite locations are Rye, Blairgowrie, Portsea and Flinders Piers, as well as Ricketts Point Marine Sanctuary. Portsea and Flinders Piers are also home to Weedy Seadragons, which can be spotted even from the surface, depending on the visibility on the day. The more time you spend in the water and the more familiar you become with these sites, the more species of marine life you start to notice — from tiny, perfectly camouflaged creatures to some of the Bay’s larger residents.

Mosaic Leatherjacket.

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Shorthead Worm Eel

Once I get closer to the bottom, I start looking around very slowly for the next subject to photograph. There are Nudibranchs almost anywhere you look. Southern Velvetfish are masters of camouflage, but once you spot one for the first time, you start seeing them again and again. The Blue-Ringed Octopus is shy and

timid, yet I still encounter one or two on almost every night dive. The always grumpy-looking Little Scorpionfish is pure entertainment to watch while hunting — its whole body lifts off the sand in a sudden jump when it strikes at its prey.

A Blue-Ringed Octopus on the hunt, flashing its electric blue warning rings.

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What a schnozzle! The snout of a Weedy Seadragon up close.

Serrated Solar Nudibranch

visitors. During one night dive right under Rye Pier, I encountered a Hale’s Wobbegong close to three metres long — an unforgettable surprise in the dark.

During dives, I often get approached by huge Smooth Rays; some of them even swim over me when I’m lying on the bottom taking photos. There’s always a chance to see a Seal. Occasionally, there are some truly unexpected

A Southern Velvetfish swaying in the surge, perfectly mimicking a piece of drifting weed.

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That permanently grumpy look — a Little Scorpionfish up close.

Depending on the location, you can encounter Gobies, Blennies, Leatherjackets, Seahorses, Pipefish, Eels, Flatheads, Stingrays, Smooth Rays, Moonlighters, Old Wives, Sweep, Anemones, Decorator Crabs, Hermit Crabs, Stargazers, Gurnard Perch, Cobbler, Cuttlefish, and many other species.

Once, I even stumbled upon a mating pair of Southern Bobtail Squid. Moments like these are a reminder that even at night Port Phillip Bay is full of life, if you take the time to slow down and look. When diving at night, be extra careful with

A Little Scorpionfish, a tiny ambush predator

Feeding Bobtail Squid

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Above: Face to face with a 3-metre Hale’s Wobbe gong under Rye Pier. Less than 50 cm away, and she couldn’t have cared less.

Below: Southern Sand Octopus

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Gunn’s Leatherjacket

conditions during planning. Let people know where you plan to go and your approximate entry and exit times, carry at least two torches, and always dive with a buddy who is as confident and competent as yourself. Vadim Belakhov

Freediver & Underwater Photographer Instagram: https://www.instagram.com/freediving.visions Facebook: https://www.facebook.com/vadim.belakhov YouTube: https://youtube.com/@freediving.visions Email: vbelakhov@gmail.com

Polycera hedgpethi feeds on the bryozoans Bugula neritina,

Pink Haliclona Nudibranch — endemic to Australia.

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Shark Feeding Photography.

During your travels to dive destinations Worldwide you will find dive operators providing shark feeding experiences. The fact remains that sharks are wary creatures and the only way photographers can create images of them is by attracting them close with bait. This does involve some risk so it’s very important to arm yourself with as much knowledge as possible to reduce the risks. 1: Wear a full length suit, do not have any garments or gear that is white and wear black gloves to disguise your white hands. White resembles the white carcass of fish bait. 2: Be alert to the direction of current flow or water movement to ensure you are up current from the bait odour or small particles of bait in the water column. Otherwise you will get lots more unwanted attention from the sharks. 3: Stay close to the seafloor so the sharks have more room to avoid you. 4: Ensure the operators are very experienced and respected for their expertise in shark feeding management.

5: Reduce movement, stay calm and stay close to the dive guide. 6: Listen very carefully to the pre dive instructions and follow the instructions. Location: Gardens of the Queen, Cuba. Genre: Wide Angle With Strobes. Photo Data: Nikon D800, Nikkor 16-35 mm Zoom Lens. ISO 200, F8 @ 1/80 th second. Seacam Housing & Strobes. Photo Hints: The action can be fast and furious, especially with Reef Sharks, they have been described as `Being In A Room Full Of Flying Razorblades’! Ensure you have all your camera & strobe settings programmed before the feeding starts. Use long strobe arms to reduce backscatter from particles of fish bait in the water column. Interesting Facts: It is very rare for participants to be bitten. And on the rare occasion it has happened, the victim was not following the rules. To be fair, some of those accidents pre date all the rules we learnt the `Hard Way’ Species Name: Caribbean Reef Sharks

Kevin Deacon is a pioneer of Underwater Photography. His images have been published World Wide in prestigious books, magazines and advertising media. Kevin & Cherie Deacon operate DIVE 2000 based at Sydney's, Northern Beaches providing Photo Guided Marinelife & Photo Guided Africa Wildlife Safaris. Sales of Seacam Underwater Photographic Equipment & Photography Training.

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The Little Shop of Horrors

by David Strike

Going diving is heaps more fun than monitoring the marketing pages of the business press, but if some diving operators hope to keep their heads above water then they may need to catch up on their reading.

David Strike. January 2026

to master the underwater hand signals for saying, “ I’m cold! I have serious doubts about the quality of your rental equipment and this is the sixth time we have swum past this abandoned supermarket trolley! When will I be exposed to the fun, the excitement and the exotic marine life as promised in the glossy promotional brochure that you handed to me when I first enquired about diving?”) There are lots of reasons for this attitude. But the most common is that a handful of instructors and dive shop owners still regard diving as an alternative lifestyle rather than a business. Oblivious to the need for profit and customer service, their shop premises usually reflect a poverty of thought and pocket that keeps the business constantly teetering on the brink of financial ruin. Not that their stores are ever empty. Like ‘R Gang’s Klub-house’ , there’s usually at least half-a-dozen ‘dive-shop groupies’ with names like “Buggalugs” and “Zombie”, always hanging around drinking coffee, telling implausible tales about near-death underwater experiences and loudly advising would be customers that the regulator they were thinking of buying is $17.56 cents cheaper at a shop on the other side of town.

The Little Shop of Horrors

Going diving is heaps more fun than monitoring the marketing pages of the business press, but if some diving operators hope to keep their heads above water then they may need to catch up on their reading. Obsessed with teaching diving - probably because it’s the only aspect of the diving business that they actually understand - a few instructors and dive store owners continue to regard the certification process as an end in itself rather than the first step in building long term customer relationships. Pitching diving against the instant gratification culture of fast foods and bungy jumping, they make no attempt to sell and promote it as a unique, equipment intensive, adventure activity with rewards that more than repay the time spent in learning. Opting instead for the line of least resistance they heavily discount the price of courses and place a continuing reliance on slogans like, “Learning to dive has never been easier!” (A strange claim when we all know that it takes at least four days just

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With insufficient turnover to afford professional, service-oriented staff - and a need to maintain cash-flow by teaching courses - some dive operators tolerate the presence of folk like these because of their willingness to, “mind the store for a few days”, without pay. An act of folly that helps prove that although learning to dive might be easy, actually going diving once you’re certified is an altogether different kettle of kippers. I stumbled across this practice recently when, following the advice given to divers of always seeking an orientation to new diving areas, I telephoned a local dive store: “Hello! I’m planning a week-end dive trip for a large group and I’d like some preliminary information on your area” “You’ve come to the right place. We’ve got some of the best diving in the world! You must have heard of Apocalypse Reef. It’s where the offshore sewage outlet empties. Even on a bad day, you can find things floating around out there that you’ll never see anywhere else.”

Except at the moment. Last week one of our divers fired his spear-gun through the RIB’s inflation tube and the owner, Jack, hasn’t got around to patching it yet - but usually every day.”

“What about hire equipment?”

“Right at the moment, Jack’s using both sets on a course that he’s teaching. But we’ve got a few bits and pieces of second-hand gear for sale.”

“And what’s the best time of the year to dive in your area?”

“Ah! Now that’s a good question, isn’t it? Jack’s the best person to answer that and he’s out diving at the moment. Why don’t you call him back sometime next week. Make it in the morning, though. He’s not usually sober after lunch.” It’s almost as if some dive operators are genuinely concerned by the thought that if every certified diver in the world elected to go diving on the same day and at the same time, then the global rise in sea levels might cause devastating coastal flooding. And that, of course, would put them out of business.

“What about boat dives?”

“Every day regardless of the sea conditions.

—-ENDS—-

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