🏰 History & The Great Khanderi-Underi Island Wars
Resting low upon the sapphire waters of the Arabian Sea just 1.5 kilometers off the tranquil shores of Thal Beach in Raigad district, Underi Fort (also spelled Oondari Fort) is one of Maharashtra's most historically dramatic and intriguing offshore island fortresses. Built in January 1680 CE by **Siddi Qasim (Yakut Khan)**, the naval admiral of the Janjira Siddies acting under the authorization of the Mughal Empire and in close tactical alliance with the British in Bombay, Underi was engineered as an urgent counter-fortress directly facing **Khanderi Fort (Kanhoji Angre Island)**, which **Chhatrapati Shivaji Maharaj** had fortified just months earlier.
The twin islands of Khanderi and Underi (located barely 2 kilometers apart) became the epicenter of the ferocious **Khanderi-Underi War of 1680**.
Maratha naval forces under commanders Maynak Bhandari and Daulat Khan launched daring naval assaults in small rowing gallivats to dislodge the Siddies, while Siddi Qasim and British warships pounded Maratha positions from Underi.
For sixty years, Underi remained a heavily armed Siddi naval garrison.
In 1740 CE, the Maratha Navy under **Manaji Angre** supported by Peshwa forces launched a coordinated amphibious assault, successfully capturing Underi Fort and hoisting the saffron Maratha flag (*Bhagwa Jhenda*) atop its bastions.
In 1818, following the Third Anglo-Maratha War, Underi was ceded to the British East India Company.
🏛️ Architecture & The Island Bastion Blueprint
Underi Fort is a compact, highly fortified island citadel:
1. The 16 Basalt Sea Bastions
Measuring approximately 300 meters in circumference, the island is completely surrounded by dressed black basalt walls up to 15 feet high, reinforced by 16 rounded bastions fitted with cannon embrasures designed to withstand high Arabian Sea swells.
2. Mounted 17th-Century Artillery Cannons
Scattered along the ramparts are several preserved iron cannons pointing across the narrow sea channel toward sister fortress **Khanderi Island**.
3. The Landward Boat Landing & Arched Gate
Entry is through a sheltered arched stone gateway facing east toward Thal village, protected by flanking towers and heavy wooden door pivots.
4. Rock-Cut Rainwater Cisterns
The center of the rocky island contains hand-hewn water cisterns that collected freshwater during monsoon rains to sustain the garrison.
🛡️ Present Condition & Thal Coastal Heritage
Underi Fort is maintained as a protected national monument under the Archaeological Survey of India (ASI, Mumbai Circle). Because of its offshore location, the fortress remains largely uncommercialized, retaining an enchanting, rugged, and authentic historical aura.
Adventure travelers and history enthusiasts hire local motorized fishing boats from **Thal Beach or Navgaon Jetty** to circle the island and land on its rocky shore (subject to sea conditions and high tide clearance).
Underi is an essential highlight of the **Alibaug Maritime Forts Circuit**, easily combined with **Khanderi Fort (2 km by boat)**, **Thal Beach & Fishing Village (1.5 km)**, **Varsoli Beach (5 km)**, **Kolaba Fort (8 km)**, and **Kihim Beach (8 km)**.
The coastal waters around Underi offer peaceful sea views, passing container ships entering Mumbai harbor, and flocks of seagulls and terns skimming the waves.
🧭 Visitor Guide: How to Reach, Timings & Logistics
Essential visitor details for exploring Underi Fort:
- Location: Located in the Arabian Sea off Thal Beach, Thal, Alibaug taluka, Raigad district, Maharashtra 402207, 6 km north of Alibaug and 15 km south of Mandwa Jetty.
- Timings & Fee: Open daily from 7:00 AM to 5:30 PM (Daylight hours only). Entry to the fort is free. (Local fishing boat hire from Thal Beach ranges from ₹1,200 to ₹2,500 per boat for a round-trip group excursion).
- Boat Access Season: Best visited from **October to May** when sea waters are calm. Boat trips are suspended during the monsoon season (June to September).
- Nearby Attractions: Combine your boat excursion with Khanderi Island Fort (2 km), Thal Beach (1.5 km), Kihim Beach & Birding (8 km), Kolaba Fort Alibaug (8 km), and Mandwa Water Sports (15 km).
🚌 Transportation & Transit Logistics
| Transit Point | Distance | Route Corridor | Recommended Mode |
|---|---|---|---|
| Thal Fishing Village Shore | Boat 15 min | Thal Beach → Fishing Boat across Channel → Underi Island | 15-minute scenic boat ride. |
| Alibaug City Center | 6 km | Alibaug → Varsoli Road → Thal Beach Road | 12-minute auto or taxi ride. |
| Mandwa Jetty (Ferry from Mumbai) | 15 km | Mandwa → Rewas-Alibaug Road → Thal | 25-minute taxi drive. |
| Mumbai International Airport (BOM) | 110 km | Mumbai → Panvel → Pen → Wadkhal → Alibaug → Thal | 2.5-hour highway drive or 1-hour ferry combo. |
❓ Frequently Asked Questions
1. Who built Underi Fort and when?
Underi Fort was built in January 1680 CE by Siddi Qasim (Yakut Khan), the naval commander of Janjira, with backing from the British East India Company.
2. Why was Underi Fort built near Khanderi Fort?
It was built as a direct counter-fortress to Chhatrapati Shivaji Maharaj's naval base on nearby Khanderi Island, sparking the 1680 Khanderi-Underi Naval War.
3. Where is Underi Fort located?
Underi Fort is an island located in the Arabian Sea, 1.5 km off Thal Beach and 6 km north of Alibaug in Raigad district, Maharashtra.
4. How do you reach Underi Fort?
Underi Fort is reached by hiring a local motorized boat or fishing vessel from Thal Beach or Navgaon Jetty (approx. 15-minute boat ride).
5. When did the Marathas capture Underi Fort?
The Maratha Navy under Manaji Angre and Peshwa Balaji Baji Rao captured Underi Fort from the Siddies in 1740 CE.
6. Can you visit Underi Fort during monsoon season?
No, boat trips to Underi are suspended between June and September due to rough sea conditions and high waves.
7. What are the timings and entry fee for Underi Fort?
Underi Fort is open daily from 7:00 AM to 5:30 PM with free entry (boat charges apply).