The major dive centres are on the east coast in Pattaya, on the Andaman coast at Phuket, Khao Lak, Ao Nang, Ko Phi Phi, Ko Lanta, and on the Gulf Coast on Ko Tao, Ko Samui and Ko Pha Ngan. You can organize dive expeditions at all these places, rent out equipment and do a certificated diving course (B7500-11,000 for a four-day Open Water course). Phuket dive centres offer the cheapest courses. You can dive all year round in Thailand, as the coasts are subject to different monsoon seasons: the diving seasons are from November to April along the Andaman coast, from January to October on the Gulf coast, and all year round on the east coast. There are currently two decompression chambers in Thailand, one in Sattahip on the east coast near Pattaya , the other on Ao Patong in Phuket .