Andaman and Nicobar Islands (Physical Geography)

What are the Andaman and Nicobar Islands, geologically?

The Andaman and Nicobar Islands are the submerged extension of the Arakan Yoma mountain range of Myanmar. Only the highest ridges of that drowned range stay above the sea, forming a chain of about 572 islands in the Bay of Bengal, of which only 38 are permanently inhabited. They sit where the Indian plate is being pushed under the Burma microplate, a convergent boundary that shapes almost everything else here. That origin sets them apart from Lakshadweep, which formed from coral growth on a submerged plateau, not a drowned mountain range. Andaman and Nicobar form a single Union Territory, with Port Blair, now renamed Sri Vijaya Puram, as its capital.

What separates the Andaman group from the Nicobar group?

The Ten Degree Channel, running along 10°N latitude, separates the Andaman group in the north from the Nicobar group in the south. Specifically, it runs between Little Andaman, the southernmost Andaman island, and Car Nicobar, the northernmost Nicobar island. It’s a different channel from the Gulf of Mannar or Palk Strait, which sit near Tamil Nadu and Sri Lanka, not here. Saddle Peak, on North Andaman at about 733 metres, is the highest point in the whole group, taller than Mount Thuillier’s 642 metres on Great Nicobar, an easy pair to mix up.

What holds India’s only confirmed active volcano?

Barren Island, in the Andaman group, holds India’s only confirmed active volcano. That volcanic activity comes from the same plate boundary that pushed the islands up in the first place. The Andaman and Nicobar Command, headquartered at Port Blair, is India’s first and only tri-service theatre command, combining the Army, Navy, and Air Force under one officer. It was set up in 2001, after the Kargil War exposed gaps in service coordination, specifically to watch over the Strait of Malacca approach. It is not a British-era creation, whatever some exam options claim.

What did the 2004 tsunami do to these islands?

On 26 December 2004, an undersea megathrust earthquake off Sumatra sent a tsunami into the islands, killing over 2,000 people and leaving roughly 40,000 homeless. In the southern Nicobar Islands, the tsunami reached heights of up to 15 metres. That earthquake permanently shifted parts of the coastline, sinking some areas and raising others, along the same fault that feeds Barren Island’s volcano. Indira Point, on Great Nicobar, India’s southernmost point, was one of the most striking casualties: the ground under its lighthouse sank by about 4.25 metres, leaving much of the tower standing in seawater. The original lighthouse was abandoned unmanned after the disaster, and a new one finally became operational in 2018.

Who lives on these islands, and how did the British use their isolation?

The islands’ indigenous groups include the Great Andamanese, Onge, Jarawa, and Sentinelese in the Andamans, and the Nicobarese and Shompen in the Nicobars. The Sentinelese, on North Sentinel Island, remain almost entirely uncontacted, and outside visits there are legally prohibited. Between 1896 and 1906, the British built the Cellular Jail at Port Blair to exploit this same remoteness, earning it the name “Kala Pani,” or black waters. It later held freedom fighters including Vinayak Damodar Savarkar, cut off from the mainland by the same sea that isolates these islands’ tribes today. The jail now stands as a national memorial.

What cleared its last hurdle here in 2026?

In February 2026, the National Green Tribunal cleared the Great Nicobar Island Development Project, dismissing petitions that sought to stall it. Its centrepiece is a container transshipment port at Galathea Bay, on Great Nicobar, just 40 nautical miles from the Strait of Malacca shipping route. Here’s why it matters here: Galathea Bay sits at the foot of Mount Thuillier, the same Nicobar peak this article’s opening section already names. (Source: The Tribune, February 2026)