Famous for Talay Nai — a spectacular landlocked saltwater lake — and its vibrant coral reefs. The visual heart of Ang Thong Marine Park.
Koh Mae Ko (Mother Island) is perhaps the most photographed island in the entire national park. Its unique geography features a hidden, landlocked emerald lake surrounded by sheer limestone cliffs, connected to the sea through underground tunnels.
Whether you're arriving by big boat or speedboat, the short but steep climb to the lagoon viewpoint is a non-negotiable part of the experience. The island also offers some of the park's best shallow-water snorkelling right off its landing beach.
A short but intense climb rewarded by one of Thailand's most unique natural wonders.
The path to the lagoon is entirely on well-maintained wooden and concrete steps. It is steep, but much shorter than the 500m viewpoint at Koh Wua Ta Lap.
About 5-7 minutes of steep climbing. This leads to the main viewpoint overlooking the lagoon.
From here, you can see the lagoon on one side and the open sea on the other. Breathtaking.
You can continue down the other side of the ridge right to the edge of the lagoon itself. Note: Swimming in the lagoon is strictly prohibited to preserve the ecosystem.
Visibility: The color of the lagoon changes with the sunlight. Mid-morning is best for the brightest emerald tones.
Shoes: While wooden steps are easier than rock, they can be slippery when wet. Wear shoes with decent grip.
Photography: A wide-angle lens is essential to capture the full scale of the lagoon and its cliffs.
The Emerald Lagoon is included in almost every full-day tour. Compare the best options below.