Sai Yohk National Park is a protected natural area in Kanchanaburi, situated along the Kwae Noi River (fig.) near the Thai–Myanmar border.

This small army of park rangers helps protect its flora and fauna which comprises of a rich assemblage of mammals, birds, reptiles, and freshwater fish.

The park is home to the Bumblebee Bat, the world's smallest known mammal, and the Gaur (fig.), the world's largest wild bovine animal.