Lake Pontchartrain is an estuary located in southeastern Louisiana in the United States. It covers an area of 1,600 km2 with an average depth of 3.7 to 4.3 m. Some shipping channels are kept deeper through dredging. It is roughly oval in shape, about 64 km from west to east and 39 km from south to north.
The lake is crossed by the Lake Pontchartrain Causeway, the longest continuous bridge over water in the world. A power line also crosses the lake. Its towers stand on caissons in Lake Pontchartrain, and its length can be used to visually demonstrate the curvature of the Earth.
