Old Mission Peninsula in the context of Grand Traverse County, Michigan

Grand Traverse Bay (/ˈtrævərs/ TRAV-ərss) is an arm of Lake Michigan, located along the west coast of the Lower Peninsula of Michigan. The bay is separated from the rest of Lake Michigan by the Leelanau Peninsula. The bay is some 32 miles (51 km) long, ranges from 7 to 10 miles (11 to 16 km) wide, and up to 620 feet (190 m) deep in spots. It is the second-largest bay of Lake Michigan, behind Green Bay.

Grand Traverse Bay is further divided into an East Arm and West Arm by the 18-mile-long (29 km) Old Mission Peninsula. At the head of both arms of the bay is Traverse City, the largest city in Northern Michigan. The area surrounding the bay is renowned for its fruit production, especially for cherries and viticulture.

Traverse City (/ˈtrævərs/ TRAV-ərss) is a city in the U.S. state of Michigan. It is the county seat of Grand Traverse County, although it partly extends into Leelanau County. The city's population was 15,678 at the 2020 census, while the four-county Traverse City metropolitan area had 153,448 residents. Traverse City is the largest city in Northern Michigan.

Traverse City is at the head of the East and West arms of Grand Traverse Bay, a 32-mile-long (51 km) bay of Lake Michigan. Grand Traverse Bay is divided into arms by the 18-mile-long (29 km) Old Mission Peninsula, which is attached at its base to Traverse City. The city borders four townships–East Bay, Elmwood, Garfield, and Peninsula–all of which are primarily suburban.