Sagar island is an island in the Ganges delta, lying on the mainland rack of Bay of Bengal around 100 km 54 nautical miles south of Kolkata.This island frames the Sagar CD Block in Kakdwip subdivision of South 24 Parganas District in the Indian State West Bengal. The island is vast — with a region of 224.3 km², lying between 21°36' to 21°56' north scope and 88°2' to 88° 11' east scope. It has 43 towns and a populace of more than 160,000.
The biggest town is likewise named "Ganga Sagar" or "Gangasagar". In spite of the fact that Sagar island is a piece of Sunderban Administration, it doesn't have any tiger residence or mangrove woods or little stream tributaries as is normal for the general sunderban delta. This island, otherwise called Gangasagar or Sagardwip, is a position of Hindu journey. Consistently upon the arrival of Makar Sankranti 14 January, a huge number of Hindus assemble to take a sacred plunge at the juncture of waterway Ganges and Bay of Bengal and offer petitions in the Kapil Muni Temple.