Gangasagar is primarily important for the Temple Of Kapil Muni, the great saint who according to myth was Lord Vishnu. Kapil Muni was the son of Kardam Muni. As per the mythology,it was said that Kardam Muni had to go through his marital life according to the directions of Lord Vishnu, but Muni agreed this only under a condition & as per the condition Kardam Muni wished Lord Vishnu to take birth as his son. As per this condition Lord Vishnu had taken birth & was named as Kapil Muni. .
As per mythology Ruler of Ayodhya & the 1300th ancestor of Lord Rama, king Sagar chose to perform the Ashwamedha yagna for the 100th time. Indra - the King of Gods was jealous of King Sagar’s success for which he kidnapped and hid the Yagya horse in the hermitage of Kapil Muni (Patal) at Sagardwip. As the horse didn’t turn up, King Sagar ordered his 60,000 sons to track down the horse. After burning down forests and uprooting life and property, they finally arrived where Sage Kapil was sitting in meditation with the horse tied beside him to which the enraged prince condemned Kapil as a thief and attacked him.
Kapil Muni in an act of anger turned the 60,000 sons of king Sagar into ashes. It is said that as per the instructions of Kapil Muni, Bhagirathi the only grandson of King Sagar, mediated over years to persuade River Ganga to step down from heaven to Earth to wash the mortal remains of his ancestors and bless them with salvation thus making it a holy place. As per the myth, the souls were liberated on the day of “Makar Sankranti”, so to release one’s own souls from pain, sin & to earn virtue people come here from all over India & take a holy dip into this holy Sagar Island. The pilgrims expect all their wishes to be fulfilled & attain moksha after a dip in the freezing waters.
On that day pilgrims from all over India & World come to take bath in the Gangasagar to get rid of all the sins and simultaneously to earn virtue. They also offer puja to the great saint-Kapil in his temple which is run by the Ramanandi saints of the Hanuman Garhi of Ayodhya. Initially one of the zamindars of the then Sagardwip—Jaduram migrated from Midnapur appointed a priest from that group of saints of Ayodhya and ultimately after sometimes they demanded and established their claim over the temple. According to them as the myth is related with Ayodhya and with the forefathers of Ram, it is believed that they claimed themselves to be the actual owner of the temple.During the time of holy bathing ceremony, a large fair is held which is known as Gangasagar Mela. Except this great festival, it is also observed that throughout the year people come to visit the place.