ALERT DIVER ARTICLES

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DAN Southern Africa
In most countries, fishing regulations limit the minimum size of individual fish that can be caught to allow fish to achieve maturation so their populations can be replenished. This type of regulation assumes that larger fish are not relatively more valuable to population replenishment than smaller fish. Fish biologists, however, have occasionally found that in some species larger females reproduce disproportionately more eggs than smaller ones.

Fishy Limits

In most countries, fishing regulations limit the minimum size of individual fish that can be caught to allow fish to achieve maturation so their populations can be replenished. This type of regulation assumes that larger fish are not relatively more valuable to population replenishment than smaller fish. Fish biologists, however, have occasionally found that in some species larger females reproduce disproportionately more eggs than smaller ones.

PARTING SHOT That weirdly cool, T-shaped, winged head belonging to the great  hammerhead shark has fascinated me since boyhood. That fascination, now stronger than ever, draws me back into the water to log the day’s fifth and sixth hours in the presence of Sphyrna mokarran. It glides in, menacing in its animal architecture, a 9-footer bristling with spiky fins, all harsh angles and shadows.

Divers Alert Network

PARTING SHOT That weirdly cool, T-shaped, winged head belonging to the great hammerhead shark has fascinated me since boyhood. That fascination, now stronger than ever, draws me back into the water to log the day’s fifth and sixth hours in the presence of Sphyrna mokarran. It glides in, menacing in its animal architecture, a 9-footer bristling with spiky fins, all harsh angles and shadows.

The water is neither clear nor blue; it's more of a murky army green. Sure, the reef is stunningly beautiful, but you surmise wide-angle photography will be incredibly frustrating with such limited visibility. A few shots, a lot of back-scatter and probably several expletives later, your suspicions are confirmed. You spend the rest of your dive thinking longingly about the macro lens sitting in your camera bag.

Seeing Green

The water is neither clear nor blue; it's more of a murky army green. Sure, the reef is stunningly beautiful, but you surmise wide-angle photography will be incredibly frustrating with such limited visibility. A few shots, a lot of back-scatter and probably several expletives later, your suspicions are confirmed. You spend the rest of your dive thinking longingly about the macro lens sitting in your camera bag.

Ocean Views, 2019 Nature's Best Photography Windland Smith Rice internat. Awards.  TRIPODFISH Palm Beach, Florida, USA By Steven Kovacs  Adult tripodfish are benthic fish that reside in the abyssal zone at a depth from 3,000 feet to more than 15,000 feet. Blackwater drift dives allow for the observation of such rare and unique animals that would otherwise go unobserved. Nikon D500, 60mm f/2.8 lens, 1/250 sec, f/20, ISO 200, Ikelite DS160 strobes (2), Bigblue video lights (3), Ikelite housing

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Ocean Views, 2019 Nature's Best Photography Windland Smith Rice internat. Awards. TRIPODFISH Palm Beach, Florida, USA By Steven Kovacs Adult tripodfish are benthic fish that reside in the abyssal zone at a depth from 3,000 feet to more than 15,000 feet. Blackwater drift dives allow for the observation of such rare and unique animals that would otherwise go unobserved. Nikon D500, 60mm f/2.8 lens, 1/250 sec, f/20, ISO 200, Ikelite DS160 strobes (2), Bigblue video lights (3), Ikelite housing

Ocean Views, 2019 Nature's Best Photography Windland Smith Rice internat. Awards.  NUDIBRANCH TRINCHESIA sp. 62 Tulamben, Bali, Indonesia By Andrey Shpatak  One of the most beautiful nudibranchs I have ever seen is this Trinchesia sp. 62 while I was diving near Bali. I haven’t seen this nudibranch anywhere else. With a little imagination, we can see a fabulous light in the dark. Nikon D800, Nikkor 105mm f/2.8 VR lens, 1/200 sec, f/29, ISO 250, Inon Z-240 strobes (2), Sea and Sea housing;

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Ocean Views, 2019 Nature's Best Photography Windland Smith Rice internat. Awards. NUDIBRANCH TRINCHESIA sp. 62 Tulamben, Bali, Indonesia By Andrey Shpatak One of the most beautiful nudibranchs I have ever seen is this Trinchesia sp. 62 while I was diving near Bali. I haven’t seen this nudibranch anywhere else. With a little imagination, we can see a fabulous light in the dark. Nikon D800, Nikkor 105mm f/2.8 VR lens, 1/200 sec, f/29, ISO 250, Inon Z-240 strobes (2), Sea and Sea housing;

Flying after pool diving FAQ | DAN Southern Africa

Flying after pool diving FAQ

Flying or travel to altitude after diving is a consideration for many divers

Diagnoses: Pulmonary bleb | DAN Southern Africa

Diagnoses: Pulmonary bleb

Consulting a physician trained in dive medicine that will recognise the inherent danger of breathing compressed gas at increased atmospheric pressures

#AlertDiverSpring2015 - Verse yourself on the important legal topics of medical questionnaires, post-dive and pre-dive logs, and safe travelling to dive sites.

DAN Legal Network

​Verse yourself on the important legal topics of medical questionnaires, post-dive and pre-dive logs, and safe travelling to dive sites. The medical enquiryTo quote a seasoned diving professional: “There is nothing underwater worth risking your life to see. Be truthful and accurate when completing your medical history questionnaire.”​Those who have followed the ongoing series of discussions about ...

#AlertDiverSpring2015 - The DAN-SA Hazard Identification and Risk Assessment programme promotes a culture of safety at diving businesses. Learn about the importance of caring for your staff members and clients.

Caring For Your People

​The DAN-SA Hazard Identification and Risk Assessment programme promotes a culture of safety at diving businesses. Learn about the importance of caring for your staff members and clients. In the Autumn 2015 Alert Diver edition, we took a broad look at how the DAN-SA Hazard Identification and Risk Assessment (HIRA) programme intends to change the way in which diving businesses approach safety. Th...

#AlertDiverSpring2015 - The DAN-SA Hazard Identification and Risk Assessment programme promotes a culture of safety at diving businesses. With proper care for your facilities, clients are assured that your business is serious about safety.

Caring For Your Facilities

​The DAN-SA Hazard Identification and Risk Assessment programme promotes a culture of safety at diving businesses. With proper care for your facilities, clients are assured that your business is serious about safety. A diving business requires three things to serve its clients, namely the right water environment, the right people and the right facilities. Individual diving businesses use differe...

#AlertDiverSpring2015 - In a diving emergency, divers can count on the 24-hour DAN-SA hotline for prompt and vital information.

What to Know When Calling the Hotline

​In a diving emergency, divers can count on the 24-hour DAN-SA hotline for prompt and vital information. The DAN-SA hotline is a 24/7/365 service that is available to everyone, whether you are a DAN-SA member or not. To call the DAN-SA hotline within South Africa, call 0800 020 111; or outside of South Africa, call +27 828 10 60 10. Please note that all calls are recorded. WHEN SHOULD I PHONE TH...

#AlertDiverSpring2015 - We investigate the correlation between diving with air or nitrox and the onset of fatigue, especially since divers report feeling less tired after diving with nitrox.

Air, Nitrox & Fatigue

We investigate the correlation between diving with air or nitrox and the onset of fatigue, especially since divers report feeling less tired after diving with nitrox. For decades compressed air has been the standard and most widely-used breathing mix in recreational diving. Breathing-gas mixtures with a lower nitrogen content and higher oxygen content (enriched air nitrox) have gained popularity...

#AlertDiverSpring2015 - When diving, it is essential to prevent the loss of consciousness underwater at all costs. Learn what causes to look out for in order to manage and minimise the risk of incapacitation.

Loss of Consciousness

​When diving, it is essential to prevent the loss of consciousness underwater at all costs. Learn what causes to look out for in order to manage and minimise the risk of incapacitation. Humans are not designed for living underwater. Diving is, and remains, a very unnatural activity. The only way to engage in, and return safely from, prolonged submersion is by learning and following certain proce...

#AlertDiverSpring2015 - The unequal equalisation of one’s ears can cause a type of dizziness described as alternobaric vertigo, a common cause of vertigo that occurs in divers.

Understanding Alternobaric Vertigo

The unequal equalisation of one’s ears can cause a type of dizziness described as alternobaric vertigo, a common cause of vertigo that occurs in divers. THE PRESSURE ENVIRONMENT Learning how to equalise ear pressure is part of every diver’s basic entry-level training. Whether one is breathing compressed gas or freediving, changing depth requires the equalisation of one’s middle-ear pressure to ...

#AlertDiverSpring2015 - Learn about the different types of vertigo that divers experience and how they can be avoided.

Vertigo in the Diving Environment

​Learn about the different types of vertigo that divers experience and how they can be avoided. Anyone who has ever experienced the feeling of vertigo will surely agree with Bono’s words in the U2 song, Vertigo. The word “vertigo” is derived from the Latin word vertere which means “to turn”. It is a specific kind of rotational dizziness in which an individual experiences the sensation that they...