Mu Ko Tarutao National Marine Park
The mountainous islands of Ko Adang and Ko Rawi have dozens of undeveloped white-sand beaches. On Ko Adang, climb the mildly challenging trail up to Chadoe Cliff for views of Ko Lipe and other islands. Also don't miss Ko Hin Ngam, an island of polished stones believed to curse anyone who takes one. Nearby you'll find orange and purple bubble coral.
The park's other section covers Ko Tarutao, with steep mountains and wildlife roaming the virgin forest. Book a pick-up truck to the historical trail at Ao Talo Wao to learn about the abandoned prisoners who turned to piracy for survival during the Second World War. Take a kayak to explore the Crocodile Cave (don't worry, the crocodiles have vanished), or hike into the jungle to cool off at Lu Du waterfall.