Karaikal is situated on the Coromandel Coast facing the Bay of Bengal. It is a coastal enclave surrounded by the Nagapattinam and Mayiladuthurai districts of Tamil Nadu. The region is predominantly entirely flat and forms part of the fertile delta of the Kaveri River.
The geography of Karaikal is defined by a network of distributaries branching off from the Kaveri River, notably the Arasalar, Nattar, Vanjiar, Nular, Puravadaiyanar, Thirumalairajanar, and Pravadayanar rivers. These water bodies crisscross the district, emptying into the Bay of Bengal and creating a rich, alluvial soil composition ideal for agriculture. The coastline features sandy beaches and minor estuarine environments, with no natural forests or significant geological formations like mountains or deep valleys.