Koh Roi – the hidden lagoon in Phang Nga Bay

Koh Roi lies in Phang Nga Bay, north of Ao Nang, in an area full of limestone islands between Krabi, Phuket and Koh Yao. Unlike the open sea, the bay is well sheltered, so trips there are often possible even in the rainy season.

By speedboat the ride from Ao Nang takes about 45 to 75 minutes depending on route and sea state. Many big excursion boats from Krabi head elsewhere – which is why Koh Roi is often surprisingly quiet.

The entrance to the lagoon is a narrow passage in the rock. Depending on the water level you swim through, wade through shallow water or climb a short way over rocks. The boat stays outside – you experience the lagoon itself on foot or swimming.

Inside, a small space opens up, enclosed by rock walls, with green water and plants hanging from the cliffs. It is quiet; only birds and lapping water can be heard. A place that truly feels secret.

Getting in is a small adventure, but with the right preparation it is very doable for confident swimmers:

Phang Nga Bay holds more islands that combine perfectly with Koh Roi. Koh Kudu also has an inner lagoon, and Koh Nok a quiet beach for swimming and lunch. Together they make a route that is very different from the classic Krabi tours: fewer people, more nature, more sense of discovery.

Between the islands you cruise through a landscape of hundreds of karst towers. The ride itself is a highlight, especially on calm water in the morning light.

Around Koh Roi the water in Phang Nga Bay is usually calm, but sediment from the mangroves makes it less clear than at the islands further out. Snorkellers should check the outer rock walls, where fish gather between the rocks – for colourful reefs, Koh Rok or Chicken Island are better.

The real strength here is swimming and relaxing: the boat anchors in calm water, you jump straight off the stern and float against a backdrop of karst towers. Inside the lagoon it is quiet and partly shaded during the day.

Thanks to its sheltered location, Koh Roi is a good destination all year round, although the dry season from roughly November to April offers the calmest conditions. More important than the month are tides and time of day: in the morning the bay is usually glassy and the light in the lagoon soft.

In the rainy season the Phang Nga route can be the best option when the open sea towards Phi Phi is too rough. Discuss it with your captain the day before.