One of the best is Ko Rok , 30 km south of Koh Lanta, the twin islands with magnificent beaches covered by green tropical forest. Offshore is a square mile of coral reef with colorful sea life.
The water is transparency clear with over 30 meters sighting. For the one can't swim is also can enjoy and see underwater life from the boat. On the island are also have a thousand year the Banyan tree jungle, folk of big size monitor lizards and a troop of shell crabs.
On Ko Lanta have one day tour named “ Four Island Trip” . This will lead you to Ko Cheuk and Ko Waen , snorkeling among colorful soft coral with a hundred of Nemo. The trip also let you visit Ko Ngai or Ko Kradan , one of the magnificent beaches with coral reef off shore. The highlight is at Koh Mook, the small island with hidden beach at the heart call “ Emerald Cave ” . You need to swim through the darkness passageway. It is gently wider and more illumination, awaiting the tip will understand what the emerald cave is. Out side the cave is tiny beach at the middle of chimney of limestone cliff at the heart of the island.
Worth to visit Ko Phi Phi once, if you never. She is still charming as ever with a few manificant beaches holizontal by verticle limestone cliffs, viking cave and famous Maya Bay. The sea here is more clear with over 30 meters depth sighting, the snorkeling available everywhere in many tiny bay around the island.