Undheri Fort

Undheri Fort (the 1680 CE black basalt island fortress standing in the Arabian Sea off Thal coast, famed as Jaidurg and celebrated for fierce Maratha Siddi naval duels) near Alibaug in Maharashtra, stands as northern Raigad's supreme offbeat maritime fortification and island exploration landmark.

Situated 300 meters offshore from Thal village 8 km north of Alibaug, this rocky island citadel was fortified by Siddi Qasim in 1680 as a direct counter stronghold to Shivaji Maharaj's neighboring Khanderi Fort.

It's the home of encircling black basalt stone ramparts, intact cannon bastions overlooking the sea channel, rock cut freshwater storage cisterns, weathered iron cannons pointing towards Khanderi Island, and an intensely dramatic, deeply historic maritime ambiance filled with crashing ocean surf, whistling sea breezes, and panoramic views of the Arabian Sea horizon and Thal fishing harbor.

It represents a rich Maharashtra 17th century naval siege architecture heritage apex, Maratha Siddi maritime warfare history, and adventure boating where island fortresses, Kolaba sea forts, Kihim beach wadis, and Alibaug coastal trails unite in Undheri Fort.

Located offshore from Thal Beach, it sits 8 km north of Alibaug Bus Stand, 11 km south of Mandwa Ferry Jetty, 30 km from Pen Railway Station, and 100 km from Mumbai via NH 66, reached by traditional fishing boats hired from Thal harbor.

The 1680 CE Siddi Stronghold & Naval Battles with Khanderi

When Chhatrapati Shivaji Maharaj fortified Khanderi Island in 1679, the Mughal admiral Siddi Qasim seized the adjacent Undheri islet in 1680, fortifying it with heavy artillery to block Maratha supply lines.

For over six decades, the two sister island fortresses engaged in dramatic artillery duels until the Maratha Navy under Manaji Angre captured Undheri in 1740, integrating it into the Maratha coastal defense network.

Truth is, scrambling across the rugged rocky perimeter of Undheri while gazing across the water at the imposing stone lighthouse of Khanderi will make history feel thrillingly alive.

Khanderi Island, Kolaba Fort & Kihim Beach

Khanderi Island & Lighthouse: Located 3 km southwest in the open sea sits Khanderi Fort, renowned for its 1867 British lighthouse and ancient fortification walls.

Kolaba Fort & Kihim: After returning to Thal harbor, travelers can explore the coconut fringed shore of Kihim Beach or tour Kolaba Fort in Alibaug.

Undheri Fort & Island Explorer Day Plan

The Island Bastions & Maritime Fortress Trail: Morning arrival at Thal fishing village from Mandwa Jetty or Alibaug town (8:00 AM to 8:45 AM) -> negotiate and board a local wooden fishing boat at Thal harbor for a 15 minute boat ride to Undheri Fort (9:00 AM to 9:30 AM) -> disembark onto the rocky shoreline and explore the island fort for 2 hours (9:45 AM to 11:45 AM: climb the stone bastions, inspect iron cannons, view rock cut water cisterns & photograph Khanderi Island across the channel) -> boat ride back to Thal Beach (12:00 PM to 12:30 PM) -> authentic Konkani fresh fish thali lunch at a seaside restaurant in Thal (12:45 PM to 2:00 PM) -> relax in the coconut palm groves of Kihim Beach (2:30 PM to 4:30 PM) -> visit Kolaba Fort during low tide (5:00 PM to 6:30 PM) -> return to Mandwa or Alibaug for dinner.

Visiting Code & Conduct: Accessible only by hiring local fishing boats from Thal Beach; check sea tide timings with boatmen before departure; wear sturdy footwear with rubber grips for walking on slippery rock surfaces; boat trips remain suspended during the monsoon season (June to September).

After exploring the island ramparts of Undheri Fort, visit Kolaba Fort, relax at Kihim Beach, or tour Alibaug Beach.