Emerald Cave (Tham Morakot) from Koh Lanta: What to Expect

The Emerald Cave, Tham Morakot in Thai, is a sea cave on the coast of Koh Mook, an island in neighbouring Trang province south of Koh Lanta. Visitors swim through a dark tunnel and come out in a small enclosed lagoon, a hong, with a tiny sandy beach and cliffs rising on every side. That reveal, from darkness to a green-tinted, roofless chamber, is why it is one of the most photographed spots in the area.

What the visit involves

• The swim through the tunnel: the cave is entered from the sea and the tunnel is long and dark. Visitors normally swim in wearing a life jacket, often following a guide with a torch. Only go if you are comfortable in open water and enclosed spaces.
• The hidden lagoon: at the end, the tunnel opens into a small lagoon ringed by high limestone walls with a small beach and jungle overhead.
• Timing and tides: conditions in the tunnel depend on the tide and sea state, and operators plan around them. Try to arrive when it is not crowded; midday can be busy with boat groups.
• Koh Mook: the island is a low-key stop in its own right, with quiet beaches and a few small resorts.

How people usually get there from Koh Lanta

The cave is not on Koh Lanta. Most visitors reach it from Koh Lanta as part of a longtail or speedboat island-hopping day, or from Koh Mook itself by chartered boat. Many multi-island tours also stop at Koh Kradan. Itineraries differ from operator to operator, so check that the Emerald Cave is explicitly listed before you book.

Seas are rougher and many boat trips run less often in the rainy season. If the Emerald Cave is a priority, plan your trip for the dry season and confirm conditions with your operator. A national park or landing fee may apply and may or may not be included in a tour price.

A Koh Lanta tour that goes to the islands

4-island classicFrom US$42

8 hours Coastal hotels (pickup available) 4.6 (467)

4-Island Tour to Koh Kradan with Beach Lunch

• 4.6★ from 467 reviews
• A full day across four islands ending at Koh Kradan, lunch served on the beach

Best for: First-timers who want the archetypal 'Koh Lanta 4 islands' day

Check availability & price

This 4-island tour ends at Koh Kradan. Confirm on the booking page whether Emerald Cave is included in the current itinerary, as operators change routes.

Frequently asked questions

Last updated September 2026.