To the south of Phuket lie the twin islands of Koh Racha Yai (big) and Koh Racha Noi (small) which offer significantly better diving than do Phuket's western beaches. Almost all diving operators offer one day trips to both of the islands (although not on the same day) and some offer a two day live-aboard trip every week.
Racha Yai's best diving is off its east coast which makes it especially attractive during Phuket's off-season in the summer. Although visibility varies, it can be as good as 25 meters or more. A typical dive is a gentle drift along a sloping rocky face that is sprinkled with hard coral forests of many, many varieties.
Especially prominent are stag horn corals of blue and tan. Many times there are large schools of false barracudas hovering over the reef, while on the reef itself you'll see octopus and cuttlefish in addition to the more common tropical species. Divers of all levels of experience and snorkelers can visit Racha Yai with no usual hazards as the diving is easy and gentle. Water depths range between 3-30 meters.
Accommodation is available on Racha Yai in both of the pristine little bays on the northern side of the island.