People have been paddling around Thailand’s numerous shallow coral sites with goggles and snorkels for decades, but it was not until about fifteen years ago that more serious diving with proper underwater breathing apparatus really began to take off. At that time, the majority of dive shops in the kingdom ran businesses teaching basic ‘discover scuba’ and open-water courses.
As time passed, word spread of Thailand’s superb dive sites, and dive shops became increasingly competitive in the support they were able to offer advanced divers. This included offering specialized mixed breathing gases, larger volume diving tanks, double tanks, auxiliary tanks and underwater scooters. As these resources have become more readily available, seasoned divers have been able to open the door on a whole new world of exploration. An intrepid breed, they are often referred to as ‘technical divers.’
Respiration is the over-riding concern in diving. The human body is profoundly affected by the compressed gases breathed underwater. Air normally contains about one-fifth oxygen to four-fifths nitrogen — gases which when breathed at surface level are perfectly normal. But once a diver passes beyond normal recreational dive limits, they become potential killers.
Oxygen, which is essential for sustaining life, meanwhile becomes toxic beyond 60 metres and this can induce convulsions — and drowning if the regulator used for breathing through the mouth falls out.
Mixed gases are essential to extending the depth and duration of dives. Ordinary recreational divers breathe compressed air, and do not have to stop to allow for decompression on the way up. Technical divers use nitrox and tri-mix gases instead. Nitrox has extra oxygen added to the air during compression, and reduced nitrogen, which helps extend dive times and mitigate the risk of decompression sickness.
Tri-mix incorporates helium into the mix, an inert gas that reduces the risk of both nitrogen narcosis and oxygen toxicity. For deep dives of more than 60 metres, technical divers use tri-mix to go down, and nitrox for decompression when they come back up.
Two of the most popular new activities in Thailand are wreck diving, mostly in the Gulf of Thailand, and cave diving, mostly along the Andaman Sea coastline. The Gulf of Thailand falls well short of being an Asian Bermuda Triangle, but is rich in sunken wrecks resulting from misadventures in trading, piracy and war. Many stories have been lost in the mists of time but, according to one list, there are at least 179 sunken Japanese ships — or marus, as some divers prefer to call them.
Some of the biggest recent discoveries date from the Second World War. In mid-2005, a group of technical divers from Koh Tao came across a US submarine that had been sunk in 72 metres of water by the IJN Hatsutaka, a Japanese minelayer that recorded an anti-submarine action with depth charges at the time.
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Images © Bruce Konefe