Sombrero Reef is about 4 miles off Boot Key at the South end of Marathon and is marked by several buoys and a 160 feet tall lighthouse. The Sombrero Key Lighthouse was built in the 1850's and was forecast by its building supervisor, US Army Corps of Topographical Engineers, Lieutenant George Gordon Meade, to last for 200 years. It is still fully functional and in service.
Sombrero Reef is your classic "spur and groove" formation with large fingers of hard coral, rimmed with sea fans and soft corals separated by narrow sandy areas. You'll find yellowtail snappers, parrotfish, squirrelfish, nurse sharks and stingrays all around the reef. The best dive area is South of the Lighthouse (oceanside).
The depth ranges from 5 to 35 feet making this dive site excellent for beginner to advanced divers and also snorkeling.