Most of Umphang is mountainous, geographically separated from the east part of Tak Province by the Thanon Thongchai Range. In the southern part of Umphang there are the Dawna Hills and the Thungyai Naresuan Wildlife Sanctuary while in the central part near Umphang town there is the Umphang Wildlife Sanctuary. Directly east of Umphang Wildlife Sanctuary is Mae Wong National Park (in Tak and Kamphaeng Phet Province) and Khlong Lan National Park (in Kamphaeng Phet Province). The area, due to its difficulty of access, were used as a base of Communist Party of Thailand.
An important river in Umphang is Klong River which originates here and flows southward into Kanchanaburi Province.