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Drowned Karsts

The ocean meets the limestone karst in Krabi province

The limestone karsts of southern Thailand have featured in many famous movies, including James Bond’s "The Man with the Golden Gun" (hence the James Bond Island near Phuket). These dramatic crags rise from the waters edge and valley floors to vertical heights in excess of 900 metres. Providing ample pleasures for rock climbers, and cavers, they also offer a splendid backdrop for the less adventurous, claustrophobic or vertiginous.

A rock climber's dream?

These limestone karsts were formed 260 million years ago when a shallow sea, running the entire length of south Asia, slowly built up deep deposits of coral and shells which were later buried under sediments washing in from the land.

Compressed deep in the earth these calcium carbonate remains formed limestone. This was thrust up above the surface when the Indian subcontinent collided with mainland Asia some 30 million years ago. From Gualin in China, to Sarawak in Borneo, the limestone  created craggy islands on land and in water. In the South of Thailand, the provinces of Surat Thani, Phang Nga, Krabi and Trang have the most spectacular examples of this type of scenery

Limestone habitats have special characters. Rain water can easily carve through limestone and it is a rock which dissolves and drains readily. Limestone-based soils tend to be drier than other soils and support a unique flora and fauna. The limestone rock supports little soil and vegetation is limited. So plants which colonise the karst must exploit every nook and cranny where moisture is trapped.

Limestone is also cave country (in Thai "tham", although sea chambers may be referred to with the same word as a room - a "hong"). When the roofs of islands or other coastal caves collapse, the prized, blissfully private beach and secret garden of an island "doughnut" may be created.

Island centre in Ang Thong marine national park, Surat Thani province

Caves are usually associated with bats and in Thailand with the swiftlets that make the edible birds nests. Bats of many sizes roost in the caves of Thailand, including what is believed to be the world's smallest: Kitti's hog-nose bat (found exclusively in a cave in Kanchanaburi province in the west of Thailand).

Among the many plants which colonise the nooks and crannies of the karst environment are tiny bonsai-like palms, and cycads (tree-ferns). There are even some species of figs which can colonise the karst, providing a favourite food source for primates and birds.

However, even the spectacular karst environment is under threat from rapid development. The karsts of southern and other parts of Thailand are in demand for cement production. The rapid growth of Bangkok and other urban areas, as well as large-scale tourism developments has led to the destruction of many karst formations. Whole mountains are eaten away inexorably as they are passed out in limestone concessions. Some of these concessions have even been given away in national parks. One can only hope that more benign uses of these magnificent limestone features, and a slowing in the pace of development will allow time for a change in attitude and a growth in appreciation of the stunning karst environment.

A recent picture from the Bangkok Post covering the story of a mountain collapse which Royal Forestry Department officials blame on blasting for a limestone concession.

Read: "Reefs to Rainforests: Mangroves to Mountains, a guide to South Thailand's natural wonders" by T. Henley. Available at Asia Books and other bookstores. This and other guidebooks contains more information on karst development and where karst scenery can be found in the South of Thailand.

Links to Further Information on Limestone Karst in Thailand and Around the World - Most of these are tourism or activity based links. NESSThai does not endorse any of the tours or operators listed below and provides these links for information only.

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