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 Thullier, which is part of this range, has the highest elevation of any point in the Nicobars, at 642 m above sea level.