The clear and calm waters of the Gulf of Thailand around Koh Samui and its colorful coral reefs make this a soothing spot for divers to spot stingrays, barracudas, eels, and sea anemones. Divers venturing deeper into the water might even spot whale sharks, and the nudibranchs and shrimps hiding between crevices underwater make for amazing photographs.
Sail Rock has much marine life, as does the Chumphon Pinnacle Dive Site, Hin Wong, and the Southwest Pinnacles. You could swim or go on shallower dives at Green Rock, while you could spot the rare titan triggerfish at White Rock.