Barren Island

Barren Island is the only confirmed historically active volcano in India — and the only historically active volcano along the entire Andaman volcanic arc from Sumatra to Myanmar.

The volcano has been in a near-continuous state of eruption or unrest since reawakening in 1991 after approximately 150 years of dormancy.

The volcanic edifice rises approximately 2,600 m from the seafloor, but only 354 m are above sea level — the island represents merely the tip of a large submarine mountain.

The 2-km-wide caldera is breached on its western side, allowing the Andaman Sea to flood the interior and creating a spectacular partially enclosed bay.

Feral goats — descendants of animals introduced during a brief period of attempted habitation — are the island's only permanent land mammals.

The surrounding coral reefs are among the most pristine in the Andaman Sea, attracting manta rays, reef sharks, and adventurous divers willing to make the 6-8 hour boat journey from Port Blair.

Barren Island's first documented eruption was observed by British colonial surveyors in 1787, making it one of the earliest volcanological observations in the Indian subcontinent.

During active eruptions, lava flows descend through the caldera's western breach and enter the sea, creating spectacular laze plumes (volcanic steam) visible from boats offshore.

With 13 eruptions since 2005, Barren Island has been one of the most frequently active volcanoes in southern Asia over the past two decades.

The Indian Navy restricts approach to the island during eruptions, establishing a safety perimeter around the active volcano.

Narcondam Island, 140 km northeast, is Barren Island's nearest volcanic neighbor — but it is dormant and has not erupted in recorded history.

The basaltic composition of Barren Island's lava is somewhat unusual for a subduction zone volcano, where more silicic andesitic compositions are typical.