The Tsongmo Lake or Changu Lake is a glacial lake in the East Sikkim, India, some 40 kilometres (25 mi) away from Gangtok, the capital of the state of Sikkim. Its elevation is 3,780 m (12,400 ft). During the winter season the lake remains frozen.he lake surface reflects different colours with change of seasons. The lake is held in great reverence by the local Sikkimese people. Buddhist monks prognosticated the future of the country after studying the changing colours of the lake. As the lake is located in a restricted area it is essential for all Indians visiting the area to obtain permits. In case of foreign nationals special permit is essential. It’s better to go with travel agents because they will do all the documentation for our trip.