Mu Ko Ang Thong National Marine Park

By the numbers: Thailand's Ang Thong Marine National Park - SilverKris

"An archipelago of 42 islets renowned for clear blue water, underwater caves, soaring limestone cliffs, verdant jungle and white-sand beaches; among the islets is one famed for an inland saltwater lagoon called Emerald Lake. The park supports rich wildlife — more than 50 bird species including the Pacific reef heron and the white-bellied sea eagle, plus marine life such as hairy-nosed otters, sea turtles and a colorful variety of fish. Situated roughly 28 km from Koh Samui, it is commonly visited on one-hour speedboat day trips organized by local tour operators." - Delle Chan