The island Koh Mae Koh is part of the Ang Thong National Marine Park. Park is located to the north west of Koh Samui and it has more than 40 islands. The Ang Thong National Marine Park was established in the year 1980. Koh Mae Koh or Mother Island is a must to visit. There is a swimming beach as well as the stunning Thale Noi, a wide turquoise saltwater lake bordered by sheer cliffs. This is the golden basin that gives the islands their name. From Koh Samui a couple of tour operators run day trips to the park. Tours depart daily in the high season, less frequently in the rainy season.