Angthong National Marine Park is a protected archipelago of islands located in the Gulf of Thailand, approximately 30 kilometres northwest of Koh Samui. The park consists of 42 small limestone islands rising dramatically from the sea, many of which are covered with dense tropical forest and surrounded by coral reefs. Established in 1980, the area is protected as a national park to preserve its marine ecosystems, coastal landscapes and wildlife.
The islands are characterised by steep limestone cliffs, hidden lagoons, white sandy beaches and sheltered bays. One of the most well-known features of the park is Emerald Lake (Talay Nai), a saltwater lagoon located inside the island of Ko Mae Ko. The lake is connected to the sea through underground channels and is surrounded by steep cliffs, creating a distinctive natural basin that can be viewed from an elevated viewpoint reached by a short climb.
Another highlight is the viewpoint on Ko Wua Talap, the park’s largest island and administrative centre. A steep hiking trail leads to a high vantage point overlooking the archipelago, where visitors can see dozens of islands scattered across the Gulf of Thailand. The climb can be challenging due to the steep sections and tropical heat, but the panoramic views from the summit are one of the most memorable sights in the park.
Most visitors reach Angthong National Marine Park by organised boat tour departing from Koh Samui or nearby Koh Phangan. These tours usually include transport, lunch, park entrance fees and activities such as snorkelling, kayaking and short hikes. Kayaking between the limestone islands is particularly popular, as it allows visitors to explore narrow channels, caves and secluded beaches that cannot be reached by larger boats.
Because the park is a protected environment, visitor facilities are limited. Basic amenities such as toilets and a small restaurant are available on Ko Wua Talap, but most other islands remain undeveloped. Visitors planning a trip should bring sun protection, drinking water and suitable footwear for walking trails.
Weather conditions in the Gulf of Thailand can affect boat travel, particularly during the monsoon season. For the most comfortable experience, trips are usually best undertaken during calmer morning conditions when the sea is relatively smooth.
Top 5 Highlights of Angthong National Marine Park
Blue Lagoon / Emerald Lake (Talay Nai)
Emerald Lake is a striking saltwater lagoon hidden inside the limestone island of Ko Mae Ko. The lake is surrounded by steep cliffs and connected to the sea through underground channels. Visitors reach a viewpoint via a short staircase trail that overlooks the vivid green water and the surrounding karst landscape.
Google map 4.8/5
Ko Wua Talap Viewpoint
Ko Wua Talap (AKA Pha Chan Charat Viewpoint) is the largest island in the park and home to the park headquarters. A steep hiking trail leads to a high viewpoint overlooking the archipelago. From the summit visitors can see dozens of limestone islands rising from the Gulf of Thailand, making it one of the most impressive panoramic views in the park.
Google map 4.7/5
Kayaking Through the Islands
Sea kayaking is one of the most popular activities in Angthong National Marine Park. Guided tours allow visitors to paddle through narrow channels between the limestone islands, explore caves and reach quiet beaches that are inaccessible to larger boats.
Snorkelling in Coral Reefs
Several islands in the park have shallow coral reefs where visitors can snorkel and observe tropical fish and marine life. Although not the most colourful reefs in Thailand, the clear water and protected environment still provide good opportunities for beginner snorkellers.
White Sand Beaches and Hidden Bays
Many of the park’s islands contain small sheltered beaches surrounded by limestone cliffs and tropical forest. Boat tours often stop at these quiet bays where visitors can swim, relax on the sand or explore the surrounding coastline.
Google map Ko Wua Talap Beach (National Park Sign on the beach)
Google map Ko Mae Ko Beach (Emerald Lake Beach)
Google map Ko Sam Sao Beach