Ang Thong Marine National Park encompasses 42 uninhabited limestone islands 30 km northwest of Koh Samui, protecting some of the Gulf of Thailand's most pristine marine and forest ecosystems. The park's centrepiece is the Emerald Lake — a saltwater lagoon hidden inside Koh Mae Ko island, accessed by a steep 430-step trail with sweeping views over the entire archipelago. The park was the inspiration for the fictional island in Alex Garland's novel The Beach.
Highlights
- Emerald Lake — a vivid green saltwater lagoon hidden inside a limestone island
- Panoramic viewpoint over 42 jungle islands from Koh Mae Ko
- Snorkelling and kayaking through sea arches, caves, and coral gardens
- Walking trails through intact tropical forest — hornbills and monitor lizards common
How to Get There
Day tours depart from Koh Samui's Na Thon and Maenam piers daily. Tours typically run 7 am–5 pm. The park is not accessible by independent ferry — you must join an organised tour or hire a private boat.
Visitor Tips
Book a tour that includes kayaking — the sea caves and limestone archways are best explored by kayak rather than speedboat.
The Emerald Lake trail is steep; wear trainers or sturdy sandals, not flip-flops.
The park can close without notice during rough weather — confirm your tour is running the morning of departure.
Frequently Asked Questions
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Senior Travel Writer · Bangkok · 12+ years in Thailand
James has lived in Bangkok since 2014 and has visited all 77 Thai provinces. He specialises in destination guides, itinerary planning, and transport logistics. Before moving to Thailand, he worked as a travel journalist in Hong Kong and Singapore. He speaks conversational Thai and is a certified PADI divemaster.
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