French Reef is a coral reef located within the Florida Keys National Marine Sanctuary. It lies 11 km southeast of Key Largo, within the Key Largo Existing Management Area, which is immediately to the east of John Pennekamp Coral Reef State Park. French Reef is northeast of Molasses Reef.
Part of the reef lies within a Sanctuary Preservation Area (SPA), which is 37 ha in area. A number of caves and arches in a spur and groove formation are included in the SPA. (Wiki)
French Reef is one of the most spectacular reef areas in the Keys. There are dozens of ledges, tunnels, and caves; most large enough to swim through. You may want to bring a light for the caves and tunnels.
The Hourglass Cave is located 50 feet inshore from buoy F1 and the Christmas Tree Cave is located 50 feet inshore of buoy F3. Each cave offers a chance to uncover hidden sea life.
While buoy F5 marks a sandbank with coral ridges around, F6 marks a swim-through and inshore of F7 is a ledge near and old anchor. Located in the center of French Reef is the “White Sand Bottom Cave” which is the largest cave in the area. Read more at Divebuddy