ISSUE 23 ARCHIVE - DO NOT GET CAUGHT BY A GIANT WAVE

Dr Mike Gonevski

I still remember vividly the day after Christmas 2004 when I woke up to the news that a devastating tsunami in the Indian Ocean had wiped out a significant part of the coast in Southeast Asia. Among the photos of the devastation was one that stuck with me, a diver with a BCD slung over one shoulder, visibly distraught, perhaps terrified, staring at an oncoming two storey wave.

Before that there was The Day After Tomorrow. Another disastrous climate change event movie with a derelict Russian cargo ship drifting down the streets of Manhattan. Imagine getting caught in that whilst diving!

Fast forward another 12 years and I came across an article about scientists warning of a massive tidal wave if a volcano erupts in the Canary Islands. The premise is that if a volcano called Cumbre Vieja erupts on the island of La Palma, a massive slab of rock twice the volume of the Isle of Man would break away and smash into the Atlantic Ocean to cause a tsunami bigger than any recorded. A wave higher than Nelson's Column and traveling faster than a jet aircraft will devastate the eastern seaboard of America and inundate much of southern Britain.

As much as I would like to leave these Armageddon scenarios mainly to, well, Hollywood, the question that has been bothering me for some time is what you would actually do if you got caught in such a cataclysmic event. Perhaps inland diving is a safer alternative to shore diving?

For a start, you are probably diving in an old quarry or lake, where the only ripples are caused by your fellow divers getting in and out of the water. It is definitely a fresh water environment, so less problems with the cleaning of your equipment after you are finished diving. Getting to the dive site is easier as most of the time an inland diving site is very close to where you live. Getting in and out of the water is easier too, as almost all of the time it is a shore entry with a conveniently located parking, changing rooms and even warm showers! You will need less weight on your weight belt in fresh water than in salt water as, simple physics, you will be less buoyant in fresh water.

The laws of physics are still very much the same however, whether you are diving in salt or fresh water when it comes down to absorbing inert gas. The longer and deeper you go, the more of it you will accumulate. No matter whether you are using the latest dive computer or an old, tried and tested diving table, the goal is still to plan a conservative dive and to complete all the required stops in order to minimise the chance of decompression illness. The diving profile is still the main reason to end up in need of treatment in a hyperbaric chamber and a missed safety stop or a too rapid ascent to the surface is indeed still the most frequent cause for an emergency chamber visit.

The symptoms of Decompression Illness can be many and different. From aches and pains through to limb weakness, numbness and skin rashes. In a few words, anything that wasn't there before the dive can be an indication of decompression illness.

The best course of action is not to be in denial and hope that if you keep your head in the sand long enough, the problems will disappear on their own. If you are unsure, get advice. At MDC we operate a 24hour emergency phone number, and you might find that you are not that far from the nearest chamber if it is necessary to be seen in person for evaluation.

I still wonder what happened to the diver in the photo with the BCD slung over his shoulder, staring at the oncoming giant wave. I hope he made it out and he is still here to tell the tale. If this prospect is too scary for you, perhaps diving inland is the safer alternative.

Whatever you decide to do, stay safe.

Happy diving!