Kalpeni is situated approximately 287 kilometers (178 miles) west of the city of Kochi on the Indian mainland. It is a classic coral atoll, featuring a narrow, elongated landmass that arcs around a spectacular, shallow lagoon. The atoll includes the main inhabited island of Kalpeni at the southern end, and the uninhabited islets of Cheriyam in the north, and Tillakkam and Pitti in the south.
The defining geographical feature of Kalpeni is its lagoon, which is exceptionally rich in marine biodiversity, hosting vibrant coral reefs, tropical fish, and sea turtles. The soils are predominantly sandy and highly porous, formed entirely from fragmented coral and shells. Because the island sits barely above sea level, it is highly sensitive to coastal erosion, sea-level rise, and the dynamic forces of the Arabian Sea.