Thailand has thousands of kilometres of coastline with warm, clear waters and a huge variety of marine life and coral reefs making it a haven for divers and snorkellers. Thousands of people learn to dive in Thailand every year and dive shops are located all over the southern peninsula. Between sites in the Andaman Sea and the Gulf of Thailand, diving is possible year round. The best conditions are from October to April in the Andaman Sea, and May to September in the gulf. The Phi Phi Islands are one of the most popular diving destinations in the Andaman Sea due to their closeness to prime dive sites within a marine national park. Coral reefs surround the islands making it a paradise for snorkellers too. From Phuket dive trips leave for prime sites such as Red Rock, Shark Point, Koh Yao, Koh Raya and Koh Yai. Within the Gulf of Thailand, Sail Rock off the island of Samui is one of the most well known, Pattaya is famous for its wreck dives, and the live coral formations around Koh Pha Ngan are popular with snorkellers. Koh Tao is the heart of diving and snorkelling in Thailand with over 20 diving schools and its ease of access of many of its sites makes it ideal for beginners. Trips depart from Koh Tao to the Mu Koh Ang Throng National Marine Park where divers and snorkellers can enjoy the corals.