Lake Liepāja is a shallow coastal lake in western Latvia, within the city of Liepāja and the South Kurzeme Municipality. It covers 3,715 ha, is about 15 km long and up to 3.5 km wide, and has a shoreline of 53 km. The average depth is about 2 m and the maximum is about 3 m. The lake has 13 islands, and large areas are covered by reeds and other aquatic plants. The River Bārta flows into the lake at its southern end, and the Trade Canal (Tirdzniecības kanāls) in Liepāja connects it to the Baltic Sea.
The lake is part of the Liepājas ezers Nature Reserve (4,643 ha). The reserve was established in 1977 as an ornithological reserve and is now also a Natura 2000 site. The lake is an important nesting, feeding and moulting area for waterbirds, and a stopover site during migration. Breeding species include the great bittern, the western marsh harrier and the corncrake.
The lake has a diverse fish fauna. The most commonly caught species are Baltic herring, pike, tench, perch and roach. The Trade Canal is an important migration route for salmon, sea trout, vimba bream and river lamprey. A licence is required for fishing. Parts of the reserve have restricted or prohibited access, so visitors should check the rules before their trip.