Krabi is a town on the west coast of southern Thailand at the mouth of the Krabi River into the Andaman Sea. As of 2005 the town has a population of 24,986. The town is the capital of Krabi Province and Krabi district. The province is located at the shore to the Andaman Sea and is an area of outstanding natural beauty. Most notable are the solitary limestone hills, both on the land and in the sea as islands. Rock climbers from all over the world travel to Ton Sai Beach and Railay Beach to climb. These beaches form part of Krabi's Phra Nang Peninsula. Of about 154 islands belonging to the province, Ko Phi Phi Leh is perhaps the most famous, as it was the set of the movie The Beach. The coast of the province was badly damaged by the tsunami on December 26 2004. Other islands include: Ko Phi Phi Don, part of the Phi Phi Islands, and Ko Lanta, a larger island to the south. The limestone hills contain many caves, most having beautiful stalactites and stalagmites. Tham Chao Le and Tham Phi Hua To, both in Ao Luek district, contain prehistoric rock-painting depicting humans, animals as well as geometrical shapes. In Lang Rong Rien cave in 1986 archaeologists found 40,000 year old human artifacts - stone tools, pottery as well as bones. It is one of the oldest traces of human occupation in all South-East Asia. The caves of Krabi are also one of the main sources of nests of the Edible-nest Swiftlet, used to create bird's nest soup.