Great Nicobar is the largest of the Nicobar Islands of India, it is also the southermost point of India.
The island covers 1045 km² but is sparsely inhabited.
The island was severely affected by the 2004 Indian Ocean earthquake tsunami with many deaths, and was cut off from all outside contact for more than a day.
The island has several rivers, including the Alexandra, Amrit Kaur,
Dogmar and Galathea. Virtually all rivers flow in a southern or
southwesterly direction, which is indicative of the general slope of the
terrain across the island.
There are undulating hills throughout the island, with the main range running in a north-south orientation. Mount Thuillier, which is part of this range, has the highest elevation of any point in the Nicobars, at 642 m above sea level. Indira Point was submerged in the 2004 tsunami.
Trak and Treis islands Nicobar
Trak Island lies 5 miles WNW of Sombrero Point; Treis Island lies 1 mile SE of Trak Island.
Both islands are small, reef-fringed, and surrounded by sunken rocks.
A rock, which has a depth of less than 1.8m, lies about midway between Treis Island and Sombrero Point.
30 Nov 11