Emerald Cave

Emerald Cave (Tham Morakot) is a sea cave on the west coast of Koh Muk Island in Kantang District, Trang Province, southern Thailand. Part of Hat Chao Mai National Park, it is accessed by swimming or kayaking through an 80-meter dark tunnel that opens to a hidden white-sand beach enclosed by limestone cliffs and forest. The water glows emerald when sunlight enters, giving the cave its name and making it a notable natural attraction.

Visitors arrive by longtail boat from Koh Muk, Koh Libong or mainland Trang and then swim, float with life jacket, or kayak through an approximately 80-meter dark sea tunnel at low tide. Inside, the tunnel opens to a secluded circular beach with white sand, surrounded by high limestone cliffs and dense vegetation open to the sky. The sea water appears emerald green when sunlight penetrates the tunnel. There are no built structures inside; the experience is guided and tide-dependent.

Known locally as Tham Morakot, meaning Emerald Cave, named for the emerald color of the water when sunlight enters the tunnel. It is a well-known natural landmark of Trang Province and part of Hat Chao Mai National Park, promoted as a key attraction of the Trang islands.