Pondicherry is located on the Coromandel Coast, bordering the Bay of Bengal. The city is essentially an enclave surrounded by the South Arcot district (now Viluppuram and Cuddalore districts) of Tamil Nadu. The geography is predominantly characterized by coastal plains and a sandy shoreline.
The city is intersected by the backwaters of the Ariyankuppam River to the south. Several lakes and ponds dot the region, the most significant being Ousteri Lake (Osudu Lake), a vital wetland and bird sanctuary located just outside the city limits. The terrain is flat, with no significant mountain ranges or forests, making the landscape heavily dependent on the monsoon for its freshwater resources.