Cave Diving in Thailand

Posted on 03/11/09 No Comments

In the previously mentioned article on the development of technical diving in Thailand, the Tourism Authority of Thailand gives a good, if basci, overview of not only reef and wreck diving, but the increasing prominence of cave and cavern diving in the Land of Smiles.

Divers experienced in the use of tri-mix can enjoy some major challenges here. Indeed two of the largest caves so far discovered in Asia are in the vicinity of Krabi province, on the mainland near the island province of Phuket.

Sre Keow was one of the first to be explored. It is accessed through a pond of about 15 metres in diameter that was once mainly used for washing elephants. A small entrance at a depth of ten metres leads into one of the deepest caves so far discovered in Thailand.

Divers use rebreathers to reduce the tanks required for these dives. Rebreathers are a special type of underwater breathing apparatus that involve relatively small tanks. These filter out poisonous carbon dioxide during exhalation, enabling the diver to ‘rebreathe’ exhaled gas until it is fully depleted.

A small rebreather weighs around 25 kilogrammes and allows a diver to stay underwater for three or four hours. In addition, extra tanks are staged inside the cave at about the 150-metre mark. These facilitate dives to the cave’s bottom at around 240 metres.

The total dive time required for such an expedition is six to eight hours. A large plastic container the size of a children’s paddling pool is inverted and submerged, and then tied off at a depth of about 4.5 metres. This creates an underwater habitat with an air pocket where the divers can decompress in relative comfort. As the nitrogen dissipates, they drink water to rehydrate and eat if they wish.

It is uncertain how many caves suited to diving exist in Thailand since new ones are being discovered all the time in the south, and also in lakes elsewhere. Another spectacular known cave, Song Hong, is shallower than Sre Keow but offers much deeper penetration into the rock formation. It is accessed through a larger 75-metre pond which sinks to a depth of 110 metres. About twelve metres down, a relatively small entrance provides access into a vast cave – so large in fact that a light beam will not reach the cave wall on the other side.

Divers descending into the cave find survey lines fastened securely about every ten metres. They feel their way down along the primary line to a depth of about 120 metres, at which point the passage becomes more horizontal until it reaches a depth of about 140 metres.

The longest penetration of the cave so far from here onwards at the same depth is a remarkable 800 metres. The total dive time for such a feat is about six hours, and it requires a major team effort of typically two or three people. Extra tanks are staged along the route. The bottom diver uses twin rebreathers and a two-man diver propulsion vehicle (DPV) to carry him along.

 The full article can be read here.

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