The current wrapped the line around my ankle and tighten like a noose. My 30-cubic-foot safety cylinder should have provided plenty of oxygen to complete my decompression stops, but I hadn’t closed the valve after charging it, so the current rushing past the mouthpiece purged the tank. I was now trapped 20 feet beneath the surface with nothing to breathe and no one aware of my peril, hoping that my mistakes with the line and my breathing gas wouldn’t be my last.
After cylinders first enter service, an annual visual inspection and a five-year hydrostatic test are required. These requirements include cylinders used for diving and other life-support applications and cover breathing air, nitrox, heliox, trimix, oxygen for decompression and argon for drysuit inflation. How are these standards mandated and enforced? What are good and safe practices?
Where we encounter marine megafauna, we see only a tiny slice of their habitats and lives, which rarely includes feeding. These animals may travel thousands of feet vertically or migrate a few thousand miles horizontally to meet their nutritional needs. Some of them — sperm whales, for example — must do both: descend to depths of up to a mile or more to feast on aggregations of squid and roam across large swaths of the Pacific to avoid depleting their food resources in any one area.
No matter which alternate air source you choose, learn to calculate your air consumption and regularly practice emergency procedures. There are many ways to configure each type of redundant breathing-gas supply, but make sure your setup matches your training, gear arrangement and dive objectives. If a naysayer thinks your equipment choice is unnecessary, let them know that the difference between a fatal accident and an embarrassing incident could come down to a breath or two. Any redundancy is better than none.
The seven days in the Galápagos went by too quickly, and I was ready to come back before I had even left. The Galápagos National Park and the tour operators greatly respect the destination, and conservation is their primary goal. Even with all the protections in place, the fishing industry, climate change and ocean health pressure the archipelago. Every tourist dollar that goes into the Galápagos adds persuasive emphasis that this is a place that deserves ongoing and stringent protection.
Humpback whales feed in polar waters during the summer and then migrate to tropical or subtropical waters to breed during winter. Various locations offer seasonal whale-watching, but swimming with them is legal in only a few places — Tonga is one of them. Every year its warm and sheltered waters provide a nursery for the whales, which gather there between July and October after a long migration from Antarctica.
With adverse events, there is almost always a cascade in four phases: the trigger, the disabling agent, the disabling injury and the cause of death. Individually, each event is avoidable. Recognizing one at the time of occurrence is an opportunity to react and attempt to mitigate the risk before it becomes a problem. In root cause analysis of adverse events, the most significant factors are the lack of recognition and failure to react to the event.
Calling a dive is not as easy as just giving the thumbs-up signal. There are steps to follow after the signal to cancel a dive. The dive briefing should cover these procedures, and the greater the dive’s potential risk, the more attention to detail the procedures and briefing should have to make calling the dive happen as safely as possible.
Underwater photographers sometimes refer to the narrow water zone where a subject splits the surface as the Plimsoll interface. Opportunities abound here for dynamic shots achieved by angling the camera above or below the waterline. The dedicated and creative underwater photographer can capture traditional over-under split shots with a standard straight meniscus and dramatic reflections from below of the subject, the sunlight or both as part of a modified split shot or a fully underwater picture.