Bhishmadeva, the son of King Santanu, was born from his mother Ganga-devi at this place. He then studied with Brihaspati in the heavenly planets. When his studies were completed, Ganga-devi brought him back to earth and left him in the care of his father. At this time Bhishma came to see his maternal grandfather Jahnu Muni and he was told that Lord Caitanya would appear in Navadvipa-dhama. Jahnu Muni also instructed him on religious principles, political science, the Supreme Lord and devotional service. While Bhishma was lying on his deathbed of arrows at Kurukshetra, he spoke about the appearance of Lord Gauranga.
“In His early pastimes He appears as a householder with a golden complexion. His limbs are beautiful, and His body, smeared with the pulp of sandalwood, seems like molten gold. In His later pastimes He accepts the sannyasa order, and He is equipoised and peaceful. He is the highest abode of peace and devotion, for He silences the impersonalist nondevotees.” (Vishnu – sahasra-nama-stotra)
Bhishmadeva performed austerities and received darsana of Lord Caitanya. The Lord informed Bhishma that he would attain Navadvipa in the future and that he would teach King Yudhishthira the highest knowledge at the time of death.
(from Navadvipa-dhama-mahatmya, Parikrama-khanda)
Bhishmadeva is the son of Gangadevi. Since Ganga-devi appeared from Jahnu Muni, she became his daughter and thus Jahnu Muni became the grandfather of Bhishmadeva. After some time Bhishmadeva came here to meet his grandfather and grandmother. Jahnu Muni very affectionately kept Bhishmadeva at his asrama for a long period, during which he taught him about dharma. Bhishma passed this knowledge on to Yudhishthira while lying on the battlefield of Kurukshetra on a bed of arrows. While staying in Navadvipa, Bhishmadeva received bhakti and therefore became famous as a great Vaishnava. The island of Jahnudvipa is therefore very purifying. Only the most fortunate people eternally reside here.” That day Lord Nityananda, along with His associates, stayed in Jahnudvipa in the house of the devotees. The next morning He took all the devotees to Modadrumadvipa.