Emerald Cave (Tham Morakot), Ko Muk
An 80-metre sea tunnel through a limestone cliff that opens into a hidden emerald lagoon with a tiny beach ringed by sheer jungle walls; reached only by swimming or kayaking in.
- Category
- Caves
- Entrance fee
- National park fee applies, roughly 200-400 THB as of 2026, usually included in the day-tour price; confirm locally
- Hours
- Daylight and tour-dependent; best in the 2-3 hours around midday; often inaccessible in rough low-season seas
- Best time
- Nov-Apr calm season; arrive near midday when sunlight lights up the water
- Time needed
- Full-day tour (cave portion under 1 hour)
- Difficulty
- Moderate (an ~80 m swim through a dark sea tunnel, part in pitch dark with a guide line and life vest)
About Emerald Cave (Tham Morakot), Ko Muk
Emerald Cave is genuinely spectacular. You enter through a sea tunnel bored through a limestone cliff, part of it in pitch dark, and come out into a hidden emerald lagoon with a tiny beach ringed by sheer jungle walls. There's no other way in but to swim or kayak through, which is exactly what makes it feel like a discovery.
The honest downside is the crowds. At peak times it can become a conga-line of tour groups all funnelling through the tunnel at once, which breaks the magic a bit. It's also not for non-swimmers or the very nervous, given the dark swim on a guide line with a life vest.
Go with an early boat to get ahead of the groups, and aim to be there near midday when the sunlight lights up the water. It's a dry-season trip, since rough low-season seas often make it inaccessible.
Highlights
- Sea tunnel through a limestone cliff, part in pitch dark
- Hidden emerald lagoon with a tiny beach ringed by jungle walls
- Reached only by swimming or kayaking in
- Water glows near midday when the sun hits it
Tips
- Go with an early boat to beat the conga-line of tour groups
- Not for non-swimmers or the very nervous; it's a dark swim on a guide line
- Aim for near midday when sunlight lights up the lagoon
- Dry-season only; rough low-season seas often make it inaccessible
How to get there
Long-tail or speedboat day tour from Saladan pier to Ko Muk, roughly 1.5-2 hours; the cave itself is entered only by swimming/kayaking through the sea tunnel