Emerald Cave
Tinnawut Kaewnikhom
Last updated: 28 Dec 2025
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Emerald Cave (locally known as Tham Morakot) is a breathtaking natural wonder located on the west coast of Koh Mook in Trang Province. It is considered one of the most remarkable attractions in Thailand due to its "hidden" lagoon that can only be accessed through a dark sea tunnel.
The Secret Entrance and Experience
The most thrilling part of visiting Emerald Cave is the journey to get inside. There is no beach or walking path leading to the lagoon; you must enter from the sea.
The Swim: Visitors must jump from their boat into the crystal-clear Andaman Sea and swim into a small, dark opening at the base of a towering limestone cliff.
The Dark Tunnel: You will swim through a narrow, 80-meter-long tunnel. While the entrance is lit by sunlight reflecting off the water (creating a stunning emerald glow), the middle of the tunnel is pitch black.
The Experience: Most tours involve visitors wearing life jackets and holding onto each other in a "human chain" while guides lead the way with flashlights. The sound of the waves echoing against the cave walls makes it a truly adventurous experience.
The Hidden Lagoon
Once you emerge from the darkness of the tunnel, the sight is magical. You find yourself in a secluded inland lagoon (a sinkhole) surrounded by 360-degree vertical limestone cliffs covered in lush tropical greenery.
The Beach: Inside, there is a small, pristine beach with powdery white sand.
The Atmosphere: Looking up, you can see the blue sky framed by the jagged cliffs. It feels like stepping into a "lost world" or a secret paradise from a movie.
The Secret Entrance and Experience
The most thrilling part of visiting Emerald Cave is the journey to get inside. There is no beach or walking path leading to the lagoon; you must enter from the sea.
The Swim: Visitors must jump from their boat into the crystal-clear Andaman Sea and swim into a small, dark opening at the base of a towering limestone cliff.
The Dark Tunnel: You will swim through a narrow, 80-meter-long tunnel. While the entrance is lit by sunlight reflecting off the water (creating a stunning emerald glow), the middle of the tunnel is pitch black.
The Experience: Most tours involve visitors wearing life jackets and holding onto each other in a "human chain" while guides lead the way with flashlights. The sound of the waves echoing against the cave walls makes it a truly adventurous experience.
The Hidden Lagoon
Once you emerge from the darkness of the tunnel, the sight is magical. You find yourself in a secluded inland lagoon (a sinkhole) surrounded by 360-degree vertical limestone cliffs covered in lush tropical greenery.
The Beach: Inside, there is a small, pristine beach with powdery white sand.
The Atmosphere: Looking up, you can see the blue sky framed by the jagged cliffs. It feels like stepping into a "lost world" or a secret paradise from a movie.
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