Designated a National Park in 1980 in order to protect its complex ecosystem, Mo Ku Ang Thon stretches across some 100 km2 and incorporates 42 islands in the Gulf of Thailand, nestled between the mainland and the three sister islands of Koh Samui, Koh Phan Gan and Koh Tao.

The National Park status has helped to raise its profile as a fascinating tourist and diving destination, but its main aim fits with Thailand's fervent attempts to preserve its biodiversity. The Park is home to four types of forest; Evergreen, Beach, Limestone and Mangrove. On the larger islands where the mangrove forests are undisturbed, a rich variety of wildlife co-exist, including native langurs (long-tailed monkeys) and hairy nosed otters along with sea-eagles, egrets, kingfishers and sea-turtles, lizards and pythons.

In the shallow waters, never deeper than 10 metres, are mixed hard and soft coral reefs which are home to angelfish, butterflyfish, stingrays and sharks. Commercial fishing in the area takes advantage of the plentiful supply of mackerel, anchovy and squid.

The islands themselves are fascinating thanks to the interesting geology of the region, which has created unusual limestone rock formations, underground caves, provoked fascinating erosions creating mountain-top lakes and natural stone bridges which lead out to the sea. 

Worth visiting in particular is Thale Nai on Mae Ko island, the amazing emerald green salt water mountain-top lake, featured in Alex Garland's novel, The Beach. Truly stunning, with perfect white beaches and coral gardens it is well worth the hike up the mountainside to visit it.

The Park's headquarters lies on Wua Thalap island which also offers the vistor stunning white beaches and an underground cave of beautiful lotus-shaped stalactites and stalagmites.

Trekking, boating and snorkelling nature trails are on offer to provide visitors with the highlights of the Marine Park with a knowledgeable guide. 

The Mu Ko Ang Thong Marine Park is closed during Monsoon season (November and December) as the area becomes dangerous to visitors.