Сиккимдегі Тсомго көлі

Glacial lake in Sikkim, India

Tsomgo Lake, also known as Tsongmo Lake or Changgu Lake, is a glacial lake in Changu in the Gangtok district of the Indian state of Sikkim, some from the capital Gangtok. Located at an elevation of , the lake remains frozen during the winter season. The lake surface reflects different colours with change of seasons and is held in great reverence by the local Sikkimese people. Buddhist monks prognosticated after studying the changing colours of the lake.

In Sikkimese language the name Tsomgo is made of two words 'Tso' meaning "lake" and 'Mgo' meaning "head" which gives the literal meaning as "source of the lake".

The lake is surrounded by steep mountains which are covered with snow during winter. During summer the snow cover melts and forms the source for the lake.

The lake is formed in an oval shape and has a surface area of The maximum length of the lake is and has a maximum width of The maximum depth reported is while the average depth is The lake water quality is of moderate turbidity. The lake is the venue for the Guru Purnima festival which is also the Raksha Bandhan festival when the faith healers known as Jhakris of Sikkim assemble at the lake area to derive benefits from the healing qualities of the lake waters. After the winter season ends in middle of May, the periphery of lake has scenic blooms of flower species of rhododendrons (the state tree of Sikkim), primulas, blue and yellow poppies, irises and so forth. Also seen in the precincts of the lake are several species of birds including Brahminy ducks. Wildlife seen includes the red panda.

The nearby habitation of Changgu was declared a border trade market in 2003.

It is one of the biggest tourism draws in the Eastern Himalayan state of Sikkim receiving around 300,000 (3 lakh) tourists annually. The best time to visit the lake is January to March.