Ratchaburi Province covers 5200 square kilometers. The east part of the province contains the flat river plains of the Mae Klong river, crisscrossed by many khlongs. The most famous tourist spot in this area are the floating markets of Damnoen Saduak. The west of the province is more mountainous, and includes the Tanawsri mountain range. As the mountains are made mostly of limestone, there are several caves containing stalactites. Some caves are inhabited by large colonies of bats, and it is an impressive sight when they swarm out in the evening to feed. Other caves like the Khao Bin are accessible for visitors. The main river of the west part is the Phachi River.
At the left bank of the Phachi river the Chaloem Phra Kiat Thai Prachan National Park is in process of being established since 2003: It is scheduled to protect 384.39 km² of forests which had been battle ground with the Communist party of Thailand in the past.