Located about a quarter of a mile off the coast from Harnai port is the fascinating Suvarnadurg Fort. A rocky island, Suvarnadurg is about 8 acres big with stone wall bastions. There is no landing jetty at the Suvarnadurga fort. However, the landing is on the shores of the sandy beach of the rocky island.

Building of the Suvarnadurg fort is credited to Shivaji maharaj. Built for the Maratha Navy for defence purposes, the fort also had a ship building facility. The basic objective of establishing the fort was to counter enemy attacks, by the colonialists of Europe and also by the local chieftains.

Suvarnadurg fort is open to tourists from November to end of May post which the ferry service is suspended due to rains. Land forts were also built to support the sea fortress and in the past, the land fort and the sea fortress were connected by a tunnel, which is now defunct.

The fort is on an island in the Arabian sea on the west coast within the jurisdiction of Ratnagiri district, off the Kanakadurga fort and below the headland Harnai port. The nearest town is Dapoli, a hill station (near Chiplun), 17 kilometres (11 mi) from Harnai. Kanakadurga,[7] the harbour fort, built originally as a strategic link to the sea fort has a lighthouse. Harnai, near the dilapidated Kanakadurg fort, is an important harbour, which is right on the edge of the land that protrudes into the Arabian Sea. This is a natural harbour known for large fishing and marketing. It is conjectured that the Kanakadurga fort [8] and other land side forts such as Bankot fort, Fategad fort and Gova fort[9] were built primarily as look out forts for the security of the Suvarnadurg fort. There is no landing jetty at the Suvarnadurga fort. However, the landing is on the shores of the sandy beach of the rocky island. Another feature of the area is that a narrow channel separates the Gova, Kanakadurg[10] and Fattehgarh forts on the mainland.