Came down to Ko Chang for Xmas, the staff at the Windy Guesthouse in Trang advised us to go over to Ko Wai for snorkeling. Great island, stayed at Ko Wai Pakrang in a 2 bed concrete bungalow for 400 baht a night, had ceiling fan and bathroom. Now we are over on Ko Mak, staying right on the beach at Fantacia for 150 baht a night, right across from the island Ko Kham that has good snorkeling also (the Ko Kham Resort is fullybooked). People say this is the best snorkeling and diving area unless you want to go to the southern islands e.g. Ko Phi Phi/Ko Lanta.