Key West is an island in the Straits of Florida on the North American continent, at the southernmost tip of the Florida Keys. The island is about 90 miles (140 km) from Cuba.

Key West is politically within the limits of the city of Key West, Monroe County, Florida, United States. The city also occupies portions of nearby islands.

The island is about 4 miles (6.4 km) long and 1 mile (1.6 km) wide, with a total land mass of 4.2 square miles. Duval Street, its famous main street, is a mere 1.1 miles in length in its 14 block, off camber crossing from the Gulf of Mexico to the Florida Straits/Atlantic Ocean. In the late 1950s, many of the large salt ponds on the eastern side were filled in, nearly doubling the original land mass of the island. The island is 3,370 acres (13.6 km) in area.