Ko Lanta (Island), Krabi, Thailand.

The best of these is on Ko Ha Yai, where two enormous caverns are situated, their entrances at a 10-14 metre depth. A dive is best started from the reef to the west of the caverns, where there are some nice coral heads and fields of sea whips going down to a depth of 20 - 25 metres.

The caverns though, are without doubt the highlight. Divers can surface inside and see large stalactites hanging overhead, and the light coming info the caverns makes for some beautiful photographe. At the back of the east cave, is a small hole leading to a tunnel some 25m long, which ends in a chamber

Only those with appropriate training and equipment, and the relevant experience, should attempt this dive.