There can be very few divers who have newer heard of Richelieu, a world-famous site for seeing the world's biggest fish: the Whale Shark. These pinnacles, which cover an area of less than 1sq. km. can be reached on a day trip or by a live-aboard. The Whale Shark is most often found during March and April, and sometimes, as many as three can be found nearby. Amazing spectacles are always a possibility here. Richelieu also has the most abundant soft corals of any site in Thailand. Giant cuttlefish and groupers are always your underwater companions here.

Fourteen km. to the west are the Surin Islands, with the largest and most developed coral reefs in the Andaman Sea. Although there are not so many soft corals or sea fans, other corals, fish, sharks and sea turtles are so plentiful that nowhere else in Thailand can compare to this thriving underwater environment. The national park has been praised as having the best resources management policy in Thailand and is used by the UNEP as a case study in world marine resources management.

The shallow-water coral reefs of the Surin Islands are beautiful and very diverse, and also suitable for snorkellers. The deep-water areas of the reef slopes are the habitat for several rare creatures, such as Ribbon Eels, Crocodile Fish, Leaf Fish and so on. To the west of the islands is Decom Rocks, a new dive site in the Thai seas.