In this TED talk, self proclaimed “fish nerd” Pyle speaks about his work studying coral reef fish that live in the 100-200 metre depth range. This depth is too deep for scuba, and too shallow for submersibles, so Pyle pioneered the use of rebreathers (he was an early adopter, in 1994) to access this part of the ocean. This is a high risk pursuit, but the diversity and numbers of new species to be discovered here is stunning.
I first heard about Richard Pyle through Monty, who encouraged the readers of his Scuba Culture newsletter to check out an article Pyle wrote about an incident of decompression sickness when he was nineteen. The article is called Confessions of a Mortal Diver: Learning the Hard Way, and Monty is right – you should read it. Pyle actually mentions this incident right at the start of his talk. Watch below:
The four episodes of this History Channel series cover waves, tides and currents, predators, and pressure – all powerful features of the ocean that can be sensationalised (some more easily than others) and presented for shock value and as imminent threats to human life. Full advantage is taken of this fact.
This very American offering doesn’t boast the measured, mellifluous tones of Benedict Cumberbatch or Steve Toussaint as narrator, but the line-up of (mostly in-studio) guest narrators is quite impressive. Bruce Parker (The Power of the Sea), Susan Casey (The Devil’s Teeth and The Wave), David Gallo (scientist presenter of the TED Talk I mentioned here), Scott Cassell (student of the Humboldt squid), Richard Ellis (writer of a number of ocean history, art and sciencebooks), and Neil Hammerschlag (shark scientist) were familiar to me, as was big wave surfer Ken Bradshaw, from this article. The strange, uncomfortable way in which the studio narrators were filmed, with silent close ups interspersed with talking, was very annoying and must have been incredibly embarrassing to shoot. Or perhaps the cameraman took the footage when the narrators didn’t realise they were being filmed.
Unlike BBC documentaries, which tend to rely purely on incredible photography and fluent narrative to convey information, the History Channel favours a CGI-heavy approach that we encountered in Treasure Quest,Deep Sea Salvage, and also in the National Geographic SharkMen series.For the subject matter of this series – particularly the sections on waves, tides and currents – it was very appropriate and informative. The first episode, devoted to tsunamis, rogue waves and “monster waves”, made good use of CGI to illustrate the concepts as they were explained. The series was produced shortly before the Japanese tsunami of 2011 (there is a hastily tacked on “thoughts and prayers” disclaimer) and features interviews with a survivor of a tsunami in Samoa. I am fascinated by rogue waves – the whole episode could have been devoted to them but they don’t make for good television – we only have indirect evidence of their existence. Also, I could have done with more footage of giant ships battling storms, but that’s what youtube is for…
The least interesting and most irritating episode was the one devoted to the ocean’s top predators, which suggested that orcas are a serious threat to humans. As evidence, the cases of captive killer whales drowning and injuring their trainers at marine theme parks were cited. No mention was made of the psychosis that these whales suffer from as a result of confinement in a small, barren, completely unnatural environment. An incident in which orcas inexplicably rammed and sank a yacht in the Pacific Ocean is also described and re-enacted. Whether the orcas did what they did because they wanted to kill the people on board is highly debatable. There is also a half-hearted attempt to paint whales as potentially vicious killers, recounting incidents when sperm whales rammed whaling boats in the 19th century. More power to the sperm whales, I say.
The other dangerous predators were (predictably) white sharks, Humboldt squid, saltwater crocodiles and Australian box jellyfish. There was a small environmental message at the end of this episode, mentioning that squid will probably end up the top predators in our oceans if current trends – fishing out large predatory fish and global warming in particular – continue.
The third episode, on the immense pressures that objects in the deep ocean are subjected to, was very interesting to Tony and me as divers. A confusing interview with a diver whose brother got DCS on a wreck dive leaves (I suspect) much out. Were they even qualified divers? Why was he surprised that his brother felt unwell and confused as to the cause after he popped to the surface from 30 metres after a 30 minute dive?
The bulk of the third episode, however, recounts a 1981 experiment called Atlantis III in which three volunteers were taken in a saturation system to a simulated depth of 686 metres while breathing Trimix 10 (70% helium, 20% nitrogen and 10% oxygen). It took 31 days for them to decompress. The chief of the experiment, Peter Bennett, was the founder and former CEO of DAN. There’s a more information about the project here – worth a read (download the pdf slowly), and a briefer account here.
The series concludes with an episode on tides and currents, including rip currents. The massive tidal range of Morecambe Bay in the United Kingdom, is discussed at length. At low tide, up to 300 square kilometres of mudflats is exposed, and flooded again when the tide comes in. The guides who escort people out onto the mudflats when the tide is out seem like charming individuals – it is recommended not to wander around at low tide without local guidance. In 2004, the rising tide trapped and drowned 23 Chinese immigrants who were working the cockle beds – with such a large expanse of land to cover, the rising tide comes in at great speed. There is also a harrowing re-enactment of a father and his two sons getting washed out to sea in a rip current in Kauai that should make you think twice about swimming at beaches with warning signs on them.
You can get the DVDs here if you’re in South Africa. Foreigners, go here or here.
Clare and I took a tour of the National Hyperbarics facility at Kingsbury Hospital earlier this year. This is a specialised clinical hyperbarics facility, where they use a recompression chamber to treat diving injuries as well as to provide wound care. Breathing oxygen at an elevated pressure (higher than atmospheric pressure) is beneficial to healing of wounds, and also part of the first aid for decompression sickness.
In contrast to the chamber we did our chamber dive in at UCT, the National Hyperbarics chamber is for medical purposes. It’s equipped with comfortable seats for eight patients, and oxygen masks and monitoring equipment for each patient. It’s rated to 30 metres so actually wouldn’t provide a very exciting chamber dive experience despite the creature comforts!
Interior of the chamber
The team at National Hyperbarics are almost all (I think) scuba divers, and on occasion I have referred my students to them for assessment before signing up for a dive course. In addition to providing and monitoring hyperbaric oxygen therapy, the doctors are able to advise and prescribe treatment for divers with asthma and other concerns which may require medical clearance before getting in the water.
Control panel for the hyperbaric chamber
In the event that you have a diving accident in Cape Town, this is probably the chamber you’ll end up in. If you’re a DAN member (which you should be), DAN will arrange transfer to National Hyperbarics for you. If you’re not, you’ll have to contact them yourself to arrange for a medical technician to meet you at their Claremont facility should you require recompression treatment. So if you aren’t a member of DAN, visit the National Hyperbarics website immediately and save their contact number in your cellphone.
Update (February 2012): National Hyperbarics is moving from Claremont to Tokai. Their new facility is currently not open, so you can’t use their chamber in the event of an accident. Dive safely!
Update (March 2014): It doesn’t look as though National Hyperbarics is going to open for business again. If you’re concerned about which hyperbaric chamber you’ll go to if you have a diving accident in Cape Town, read this post.
Three divers approached me at the dive centre one day, requesting I take them to a dive site where they could dive to 60 metres. They wanted to test some new equipment configurations. Two were certified advanced Nitrox divers, qualified deep technical divers and had made several dives to over a hundred metres… in a lake. The third diver, like myself, was qualified to dive to 40 metres.
So we draw up a plan: they will dive to 60 metres, spend 6 minutes at that depth, ascend to 50 metres and spend 5 minutes there, then ascend to 40 metres 5 minutes thereafter and so on until the reached 6 metres where they would switch to pure oxygen to reduce the deco stop time as the current at this site is strong. The third diver and myself would meet them at 40metres.
Using a software program called V Planner we calculated that including the descent time and ascent times for each stage, at a controlled rate, we would enter the water precisely 16 minutes after they started their dive and we would meet them at 40 metres. We would then all be together for the next 30 minutes, ascending with them to their 6 metre safety stop, ensure they had both switched to pure oxygen and then leave them and return to the boat.
The plan was that we would spend 6 minutes on our descent to 40 metres and all four of us would reach 40 metres together. They were made to clearly understand that should they have a problem at any depth deeper than 40 metres we would not be able to help them as we were diving 12 litre steel cylinders on a Nitrox 32% mix, limiting our depth – and what’s more we did not have the qualifications to go to 60 metres.
We discussed the plan in great detail and everyone was set. A red SMB would be hoisted if they experienced any difficulty and a yellow would be released once we met at 40 metres.
Mistakes happen
We started our descent on time, and watching my dive computer and timer I descended at the agreed rate. My buddy, however, did not. He descended way too fast. Believing that they would be in control of their dive he descended very fast and joined them, ahead of schedule at a depth of 55 metres. They were 3 minutes behind schedule as they had struggled to come to terms with the ocean current. Now we had a problem. I waited at 40 metres, but they arrived late, and this meant I would risk going into deco before we left for the 30 metre stop.
At this point my buddy ran out of air. He was closer to the deep divers as he was reading their slates, so he grabbed the first regulator he could see: the deco tank regulator, filled with pure oxygen. At depth oxygen is toxic and can kill you in a matter of minutes. I grabbed it out of his mouth, so he grabbed my regulator out of my mouth as he was now starting to panic. He was holding onto me so tight I could not reach my octo so I reached for the octo of another diver. So here we were three divers locked together at 40 metres, each with a regulator in our mouths that belonged to someone else. I managed to get him calmed and off my cylinder and onto the octo of the deep diver with the most air. Now back to normal, we started our ascent and did the required safety stops, reached the 6 metre stop for them to switch to oxygen and headed for the surface. I reached the surface with 10 bar in my tank.
Ascending from the almost disastrous deep dive on Atlantis in Ponta do Ouro. Note the hang tank of pure oxygen.
My buddy had been to 55 m on a Nitrox mix of 32%. The maximum safe depth for this blend is 40 metres. He had almost sucked on a cylinder of oxygen at 40 metres, this is a lethal dose at depth. Mistakes happen. Be meticulous with dive planning, rehearse your incident scenarios and make sure you dive your plan.
