- Location: Two large outcrops directly South of Phi Phi Ley
- Site Depth: 0 - 30 meters
- Site Visability: 10 - 25 meters
- Currents: Mild / Moderate
- Difficulty Rating: Easy
Koh Bida Nai - is the inner of the two islands. At Koh Bida Nai there is a beautiful archway filled with tiny batfish which leads to a shallow hard coral garden. Koh Bida Nai is the larger of the two. The western sides of each island drop down vertically to a sandy bottom reaching depths of 30m or more in places. On the eastern sides the reefs tend to slope more gradually to depths of around 25 metres. In between the islands and close to Bida Nai is a small coral garden starting at a depth of about 6 metres with a wonderful swim-through at 14 metres depth.