If you're into snorkelling, Ko Ngai makes a good base. While the coral is mostly dead, the surrounding reefs and offshore islets attract schools of tropical fish. The magnificent seascapes of Ko Rok can be explored some 15 km west of Ngai (expect to pay around 4,000 baht for a daytrip by longtail), while Muk's awe-inspiring Emerald Cave and Kradan's South Reef are commonly included on boat excursions closer to Ngai. Snorkels can be rented at most resorts for 200 baht a day, and tours by longtail start at 600 baht.