The body of water in this image is Guantanamo Bay, Cuba. The city of Guantanamo is on the northeast side of the bay. The US military leases the land (yes, they send checks) around the lower half of this bay from the government of Cuba under a 1903 treaty.
Bays, Military - Bases
You can see the boundary road in the image, closely following the mostly rectangular border (it runs NE-SW through the swamp on the west side).