The bay, located within Okaloosa and Walton counties, is an inlet of the Gulf of Mexico and has a surface area of 334 square kilometres (129 sq mi).

[2][4] The tolled Mid-Bay Bridge (SR 293) crosses the bay, connecting the city of Destin to Niceville, Florida.

Wells Bridge (US 331) crosses the eastern part of the bay, connecting Freeport to the coast.

[8] As noted in a 1993 Eglin AFB report, Test Area D-55 was originally installed in the World War II era by Eglin Air Force Base with "omnidirectional radar corner reflectors" on top to be used as a radar target range.

[9] Test Area D-55 is formed by 25 arrays of 2,040 wood pilings placed east of the Clyde B.