The topography of the west is similar to that of the north; the land is composed mostly rolling hills and valleys. Part of it borders the sea.
There are two major mountain ranges: the Thanon Thongchai Range and Tenasserim Range.
There are few river basins. The major river is the Mae Klong.
It has several passes through the Teneasserim Range, commonly known as Dan
-Dan Mae Sot,
-Dan Mae Lamao,
-Dan Chedi Sam Ong,
-Dan Bongti and Dan Singkhon.