Mount Thullier (642 m) is an important mountain peak of Andaman and Nicobar Islands. It is located in :

Mount Thullier, also spelled Mount Thuillier, is the highest peak in the Nicobar Islands, reaching an elevation of 642 meters (2,106 feet) [2]. It is specifically located on Great Nicobar Island, which is the largest and southernmost island of the Nicobar group. While Saddle Peak (732 m) is the highest point of the entire Andaman and Nicobar archipelago and is located in North Andaman, Mount Thullier serves as the highest point for the Nicobar chain [1]. The peak is part of the Great Nicobar Biosphere Reserve, characterized by rich biodiversity and tropical rainforests. Geologically, the mountain consists of parallel ridges of folded turbidite sandstone and intrusive igneous rock formations like gabbro. It is a significant landmark in the Indian Ocean, bordering the Andaman Sea [2].

Sources

1. [1] https://www.britannica.com/place/Mount-Thullier
2. [2] http://indianculture.gov.in/node/2540083