Khao Yai National Park, the first of its kind in Thailand, has been a Unesco World Heritage Site since 2005 and a paradise for walking enthusiasts. On the agenda: majestic landscapes, splendid waterfalls (such as Heo Suwat), lush jungle and wildlife including tigers, monkeys, elephants and over 300 species of birds. It is advisable to notify the park rangers before setting out.