A little less known than Koh Tao and Koh Phi Phi, Koh Lanta is an excellent diving destination in Thailand with exceptional diving sites like Koh Haa. You can also go on sea excursions to paradise islands such as Koh Rok for relaxation and snorkeling. It is also the starting point for boat tours to Koh Ngai and Koh Mook islands and the famous Emerald Cave.