http://vedabase.net/sb/10/79/19-21/ talks abt the city here:
The Supreme Lord then traveled through the kingdoms of Kerala and Trigarta, visiting Lord Siva's sacred city of Gokarn?a, where Lord Dhurjat?i [Siva] directly manifests himself. After also visiting Goddess Parvati, who dwells on an island, Lord Balarama went to the holy district of Surparaka and bathed in the Tapi, Payos?n?i and Nirvindhya rivers. He next entered the Dan?d?aka forest and went to the river Reva, along which the city of Mahis?mati is found. Then He bathed at Manu-tirtha and finally returned to Prabhasa.