Mu Ko Similan National Park

Mu Ko Similan National Park offers the world-class diving and snorkeling that defines Thailand's Andaman coast, with nine islands surrounded by crystal-clear waters and vibrant coral reefs. Visibility frequently exceeds 30 meters, making it a top destination for underwater enthusiasts. This park outperforms #5 Kaeng Krachan in marine biodiversity, hosting over 200 species of reef fish and nesting sea turtles from November to February. Its iconic underwater boulders at Elephant Head Rock attract 15,000 divers annually, a number 40% higher than the runner-up marine park in this list.