Lake, southeastern Louisiana, U.S. It is 40 mi (64 km) long and 25 mi (40 km) wide, with an area of 625 sq mi (1,619 sq km).
More a tidal lagoon than a lake, it is brackish and teems with game fish. It is connected through Lake Borgne with the Gulf of Mexico and by canal with the Mississippi River . It is spanned by the Pontchartrain Causeway, at 23.8 mi (38.4 km) long, the world's longest concrete bridge, which crosses the lake north from New Orleans .