The Dry Tortugas are a small group of islands, located in the Gulf of Mexico at the end of the Florida Keys, United States, about 67 mi west of Key West, and 37 mi west of the Marquesas Keys, the closest islands.
 Still further west is the Tortugas Bank, which is submerged.
 The first Europeans to discover the islands were the Spanish in 1513, led by explorer Juan Ponce de León.
 They are an unincorporated area of Monroe County, Florida, and belong to the Lower Keys Census County Division.
 With their surrounding waters, they constitute the Dry Tortugas National Park.
The Florida Reef (also known as the Great Florida Reef, Florida reefs, Florida Reef Tract and Florida Keys Reef Tract) is the only living coral barrier reef in the continental United States.
 It is the third largest coral barrier reef system in the world (after the Great Barrier Reef and Belize Barrier Reef).
 It lies a few miles seaward of the Florida Keys, is about 4 miles (6 to 7 km) wide and extends (along the 20 meter depth contour) 270 km from Fowey Rocks just east of Soldier Key to just south of the Marquesas Keys.
 The barrier reef tract forms a great arc, concentric with the Florida Keys, with the northern end, in Biscayne National Park, oriented north-south and the western end, south of the Marquesas Keys, oriented east-west.
 The rest of the reef outside Biscayne National Park lies within John Pennekamp Coral Reef State Park and the Florida Keys National Marine Sanctuary.
 Isolated coral patch reefs occur northward from Biscayne National Park as far as Stuart, in Martin County.
 Coral reefs are also found in Dry Tortugas National Park west of the Marquesas Keys.
 There are more than 6,000 individual reefs in the system.
 The reefs are 5,000 to 7,000 years old, having developed since sea levels rose following the Wisconsinan glaciation.
The Florida Keys are a coral cay archipelago located off the southern coast of Florida, forming the southernmost portion of the continental United States.
 They begin at the southeastern coast of the Florida peninsula, about 15 mi south of Miami, and extend in a gentle arc south-southwest and then westward to Key West, the westernmost of the inhabited islands, and on to the uninhabited Dry Tortugas.
 The islands lie along the Florida Straits, dividing the Atlantic Ocean to the east from the Gulf of Mexico to the northwest, and defining one edge of Florida Bay.
 At the nearest point, the southern part of Key West is just 90 mi from Cuba.
 The Florida Keys are between about 23.5 and 25.5 degrees North latitude.
The Garden Key Light, also known as the Tortuga Harbor Light, is located at Fort Jefferson, on Garden Key in the Dry Tortugas, Florida.
 The first lighthouse, started in 1824 and first lit in 1826, was a brick conical tower.
 The lighthouse and its outbuildings were the only structures on Garden Key until construction started on Fort Jefferson in 1846.
 Construction continued until 1861, but the fort was never completed.
The Dry Tortugas Light is located on Loggerhead Key, three miles west of Fort Jefferson, Florida.
The Dry Tortugas Ferry to Fort Jefferson is a visitor attraction in Key West, Florida.
 Service is provided by the "Yankee Freedom III", a high-speed Incat-designed catamaran that takes visitors on the almost 70 mi trip out to Fort Jefferson in the Dry Tortugas National Park.
 The service is a licensed National Park Service concessioner, and the only provider of scheduled ferry access to the Dry Tortugas for a ten-year term through 2020.
The Everglades & Dry Tortugas Biosphere Reserve (established 1976) is a UNESCO Biosphere Reserve in Florida and the Gulf of Mexico.
 The 636,411 ha reserve encompasses Everglades National Park and Dry Tortugas National Park, including historic Fort Jefferson and the seven Dry Tortugas islands.
Dry Tortugas National Park is a national park in the United States about 68 mi west of Key West in the Gulf of Mexico.
 The park preserves Fort Jefferson and the seven Dry Tortugas islands, the westernmost and most isolated of the Florida Keys.
 The archipelago's coral reefs are the least disturbed of the Florida Keys reefs.
Fort Jefferson is a massive but unfinished coastal fortress.
 It is the largest brick masonry structure in the Americas, and is composed of over 16 million bricks.
 Among United States forts, only Fort Monroe in Virginia and Fort Adams in Rhode Island are larger.
 The fort is located on Garden Key in the lower Florida Keys within the Dry Tortugas National Park, about 70 mi west of the island of Key West.
 The Dry Tortugas are part of Monroe County, Florida, United States.
The Key West National Wildlife Refuge is a 189,497 acre (766.867 km) National Wildlife Refuge located in Monroe County, Florida, between Key West, Florida and the Dry Tortugas .
 Only 2,019 acres (8.171 km) of land are above sea level, on several keys within the refuge.
 These keys are unpopulated and are also designated as Wilderness within the Florida Keys Wilderness.
 The refuge was established to provide a preserve and breeding ground for native birds and other wildlife as well as to provide habitat and protection for endangered and threatened fish, wildlife, plants and migratory birds.

Question: The Dry Tortugas Ferry to Fort Jefferson is a visitor attraction in Key West, Florida, service is provided by the "Yankee Freedom III", a high-speed Incat-designed catamaran that takes visitors on the almost 70 mi trip out to Fort Jefferson in Dry Tortugas National Park, a national park in the United States about 68 mi west of Key West in which location?
Answer: Gulf of Mexico