With the reorganization of the states in 1956, the district was included in the Bombay state and since 1960, it forms a part of Maharashtra. The name of the district has been adopted form the famous sea fort of Sindhudurg. This was built by Shivaji Maharaj near Malwan and it literally means 'Sea Fort'.
One of the enduring symbols of Maharashtra's rich historical past is the Sindhudurg Fort. The fort derives its name from the combination of two words, Sindhu meaning sea and Durg meaning fort. Sindhudurg is just 510 km from Mumbai on the Goa Highway. One can take a ferry from the Malvan Port to the island fort. Also known as the Malvan Fort, this citadel is located half a kilometer away from the mainland port of Malvan. Shivaji wanted to build an impregnable island fort at a considerable distance from the supposedly unbreachable Janjira Fort and thus selected the rocky island of Kurute. The location of the fort was strategically chosen by Shivaji to counter foreign forces coming from the shore, as well as for safeguarding the kingdom from neighbouring rulers. It is also believed that the fort was constructed by Shivaji to keep a check on the activities of Siddis of Murud-Janjira, who wanted to destroy his kingdom.
Sindhudurg covers an extensive area of 48 acres with almost 2 miles of fortified rampart walls 29 ft high and 12 ft thick, comprising observation towers and 52 enormous semicircular bastions with embrasures for cannons. The top of the ramparts was accessible by stone staircases at various points. Some bastions contain hidden exit ways that lead out of the fort. The entrance to the fort is by the Dilli Darwaja to the north-east. The main gate is so well camouflaged withi n the folds of the rampart walls that it is visible only at really close quarters. A shrine to Goddess Jarimari guards the entrance to the fort. On the right, perched atop the main gate, is the fort's most prized relic - the footprint and palm impression of the revered Shivaji Maharaj, set on a slab of dry lime.