LOKTAK LAKE

Loktak Lake in Bishnupur District of Manipur is the largest fresh water lake in North–East India and the world’s only floating national park in the world, Keibul Lamjao National Park, is situated on the southeastern shore of the lake. Ironically, it was initially declared as a Sanctuary in 1966, and only subsequently turned into a National Park in 1977.
It has circular floating swamps called phumdis that are in reality pieces of land with a heterogeneous mass of vegetation, soil and organic matter at different stages of decomposition, floating on water, resembling miniature islands.
The lake covers an area of 300 sq. mtr. and serves as a source of water for hydropower generation, irrigation and drinking water in the region along with being a source of livelihood for the fishermen.
Not only humans, the lake is also a home for 233 species of aquatic plants, over a 100 species of birds and 425 species of animals.
Unfortunately, the lake is now endangered, with innumerable threats like pollution, decline in diversity of avifauna, flaura and thinning of phumdis.
Sources:
http://www.manipurtourism.gov.in/in-around-loktak-lake/
http://www.thebetterindia.com/38244/loktak-lake-manipur-floating-national-park/