Mobile Bay

Mobile Bay is a shallow inlet of the Gulf of Mexico in Alabama, bounded on the east by the Fort Morgan Peninsula and on the west by the barrier island Dauphin Island [1]. It covers 413 square miles, is 31 miles long and up to 24 miles wide, and averages about 10 feet deep, although the shipping channel exceeds 75 feet in places. The Mobile and Tensaw rivers empty into its northern end, making it an estuary, the fourth largest in the United States, with a discharge of about 62,000 cubic feet per second. The city of Mobile sits at the head of the bay on the western shore [1].

Geography

The Mobile and Tensaw rivers join the bay at its northern end, and smaller rivers feed it: the Dog, Deer and Fowl rivers on the west side and the Fish River on the east. Weeks Bay is a smaller embayment on the eastern shore. The tidal shoreline of Mobile and Baldwin counties, including all coastal bays, rivers and bayous, extends about 600 miles, and Mobile Bay accounts for about 100 of them [1][2]. The wetland region directly north of the bay is the Mobile-Tensaw River Delta.

Communities and crossings

Mobile lies at the head of the bay. On the Eastern Shore are Spanish Fort, Daphne, Fairhope, Point Clear and Bon Secour, and Gulf Shores lies on the Fort Morgan Peninsula, with the town of Fort Morgan directly south of the bay. Two bridges cross the head of the bay: Interstate 10, called the Jubilee Parkway, and U.S. 90 and 98, the Battleship Parkway. They are the primary links between Mobile and the Eastern Shore [1]. See Gulf Coast of Alabama and Bayou La Batre.

The jubilee

Along the eastern shore of the bay, fish and crustaceans swarm into the shallow water and become trapped near the shore, annually and often several times in summer. Crowds gather to harvest the seafood, and the phenomenon, called a jubilee, gives Daphne its nickname, the Jubilee City [1].

Exploration and settlement

Hernando de Soto explored the area in 1540 and his forces destroyed the fortified town of Mauvila, the source of the name Mobile. Diego Miruelo explored the bay in 1516, Alonso Alvarez de Pineda in 1519 and Panfilo de Narvaez passed through in 1528. Tristan de Luna’s 1559 effort to establish a permanent colony near Pensacola failed. In 1702 French colonists created a deep-sea port on Dauphin Island and founded the capital of French Louisiana at Mobile, and in 1711 the town moved to the head of the bay after floods [1]. See Dauphin Island Sea Lab.

Battle of Mobile Bay

The bay was a major port for Confederate blockade runners. On August 5, 1864, Rear Adm. David G. Farragut led about 14 wooden ships lashed in pairs and four monitors through Confederate defenses at the bay entrance. Fort Morgan had 46 guns and about 600 men, Fort Gaines 26 guns and about 600 men, and Fort Powell 18 guns and about 140 men. The Confederate naval force under Adm. Franklin Buchanan consisted of the ironclad Tennessee and three gunboats [3].

The monitor USS Tecumseh struck a mine, then called a torpedo, and sank within minutes, and only 21 of her 114 crew survived. Farragut’s order to press ahead through the minefield is remembered as Damn the torpedoes, full speed ahead, though historians question the exact wording. The Tennessee surrendered about three hours after the battle began, Fort Gaines surrendered on August 8 and Fort Morgan on August 23. Union fleet casualties were about 150 killed and 170 wounded. The victory closed Mobile, the last major Confederate Gulf port east of the Mississippi, and was Farragut’s last engagement and the last naval battle in Alabama [3][1].

Lighthouses

Alabama’s lighthouses were located exclusively in and around Mobile Bay and guided ships until the mid-1960s. The Mobile Point Light was built in 1822 where Fort Morgan now stands and was damaged in the 1864 battle. The first Sand Island Lighthouse was completed in 1838, was destroyed by Confederate soldiers in 1861, and was replaced by the present 125-foot tower in 1873; a hurricane in 1906 obliterated the island and swept away the keepers. The Middle Bay Lighthouse began operating on December 1, 1885 in the center of the bay, was automated in 1935 and deactivated in 1967 [4][1].

Economy

Cotton was the chief commodity shipped across the bay in the nineteenth century, and Mobile’s shipbuilding industry expanded during World War II. Forts Morgan and Gaines were built by the federal government in Alabama’s early statehood on opposite sides of the Mobile Channel to protect the coast. Dredging for the Mobile Ship Channel has removed more than 20 million cubic yards of sand from the littoral system since 1960 [1][2]. See Port of Mobile.

Ecology and hurricanes

Weeks Bay National Estuarine Research Reserve preserves 6,525 acres of the bay’s estuarine ecosystem, and intertidal sand beaches are valuable habitat for fish, crabs and oysters. More than one-third of the shoreline has been stabilized with structures, mostly vertical bulkheads, and about six miles of intertidal shoreline were lost from 1900 onward. Living-shoreline projects aim to restore beaches and wetlands [2].

Hurricane Frederic entered the bay on September 13, 1979 with winds of 145 miles per hour and destroyed the Dauphin Island bridge. Hurricane Katrina in August 2005 produced a surge of 16 feet at Bayou La Batre and 12 feet at Mobile, pushed the battleship USS Alabama off her moorings, and created a new inlet through Dauphin Island [1][2]. See Climate of Alabama.

FAQs

How big is Mobile Bay? 413 square miles, 31 miles long and up to 24 miles wide.

What is a jubilee? A natural event in which fish and crabs crowd the shallows and can be gathered by hand.

What happened at the Battle of Mobile Bay? Union Adm. Farragut ran past the forts on August 5, 1864 and closed Mobile as a Confederate port.

Which rivers feed the bay? The Mobile and Tensaw rivers, plus the Dog, Deer, Fowl and Fish rivers.

What lighthouses are on the bay? Mobile Point, Sand Island and Middle Bay.

Sources

1. Wikipedia: Mobile Bay
2. Encyclopedia of Alabama: Alabama’s Coastline
3. Wikipedia: Battle of Mobile Bay
4. Encyclopedia of Alabama: Lighthouses of Alabama

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 10, 2026Researched and drafted with AI assistanceReport an issue