Mobile Bay is a shallow inlet of the Gulf of Mexico, lying within the state of Alabama in the United States. Its mouth is formed by the Fort Morgan Peninsula on the eastern side and Dauphin Island, a barrier island on the western side. The Mobile River and Tensaw River empty into the northern end of the bay, making it an estuary. Several smaller rivers also empty into the bay: Dog River, Deer River, and Fowl River on the western side of the bay, and Fish River on the eastern side. Mobile Bay is the fourth-largest estuary in the United States with a discharge of 1,800 m3 of water per second. Annually, and often several times during the summer months, the fish and crustaceans will swarm the shallow coastline and shore of the bay. This event, appropriately named a jubilee, draws a large crowd because of the abundance of fresh, easily caught seafood.
Mobile Bay is 1,070 km2 in area. It is 50 km long by a maximum width of 39 km. The deepest areas of the bay are located within the shipping channel, sometimes in excess of 23 m deep, but the average depth of the bay is 3 m.
