Haleji Lake is a perennial freshwater lake, situated 96 kilometers from Karachi in Thatta District of Sindh Province, Pakistan.

It is 6.58 km2 (2.54 sq mi) in size and is surrounded by marshes and brackish seepage lagoons.

Haleji Lake was a saline lagoon until the 1930s and was converted into a reservoir to provide additional water to Karachi.

During World War II, additional water was required for troops stationed at Karachi.

The then-British Government of Sindh decided to increase the capacity of the lake by introducing a feeder canal from the Indus River.

Salt water was drained out and an embankment was constructed around the lake which was fed with fresh water through a canal.

The work was placed on a war footing and was completed within 24 months.

Haleji Lake is Asia's biggest bird sanctuary which hosts a huge diversity of migratory birds.

It is the wintering site for waterfowl such as cotton teal, spot-billed duck, purple moorhen and pheasant-tailed jacana.

It is also a breeding site for egrets and herons.