For directions and prices see the "Travel in Thailand" links in the side bar >>> If you're staying in Bangkok, these are the things to do.
Khao Yai National Park - Nature
They say it is one of the best in the world and it has a lot of wild animals. The park has many hiking trails, you can camp in the park and enjoy nature. If you go there in the rainy season be prepared to put up with the leeches that are plentiful at that time of year.