Far more than just a side trip from the beaches of southern Thailand, the magnificent wilds and majestic mountain lake of Khao Sok National Park are one of Asia's premier natural wonders. Khao Sok stretches over some 646 square kms and is part of a greater protected area that also includes Kaeng Krung and Phang Nga national parks and Khlong Nakha and Khlong Saen wildlife sanctuaries. Spanning over 4,000 square km between them, this is a massive protected area in Thailand, and on a map it looks like an entire province of nothing but lakes, rivers, and jungle. If you're going to visit only one national park in Thailand, Khao Sok is arguably your best choice.
Due to its rugged, mountainous and expansive terrain, the park and its surrounds have remained mostly untouched by people, and today Khao Sok teems with plants and wildlife. Wild elephants, dusky languars, leopards, bantung, a range of monkeys, snakes, and over 180 species of bird inhabit the park and surrounding sanctuaries. Equally impressive are Khao Sok's plant species, including massive bamboo trees so thick that anyone standing under them in a down pour will remain dry, and the Rafflesia Kerri Meijer flower, or simply "wild lotus" (bua phut) in Thai, which is one of the largest flowers in the world, reaching a diameter of over 75 cm when fully mature. The best chance to see one in bloom is in November or December, but be prepared for its pungent fragrance that smells something like rotten eggs.