While not as beautiful as Malaysia or Indonesia, Thailand does have its fair share of tropical forest. Khao Yai National Park, the first national park of Thailand, is the closest to Bangkok. Wild tigers and elephants are increasingly rare, but you can't miss the macaques, gibbons, deer, and species of birds. The stretch of jungle at Khao Sok National Park is probably even more impressive, and you can spend the night in the middle of the jungle.

Waterfalls can be found all over Thailand. The Heo Suwat Waterfall in Khao Yai National Park and the 7-tiered Erawan Falls in Kanchanaburi are among the most visited, but the Thee Lor Sue Waterfall in Umphang and the 11-tiered Pa La-u Falls in Kaeng Krachan National Park are equally exciting. Finally, the gravity-defying limestone formations of the Phang Nga Bay shouldn't be missed by anyone who stays in the region.