French Reef

The dive works shallow and lateral rather than deep, so the limit on your time here is gas rather than no-stop minutes. Drop in and get oriented before moving off: the reef is cut into channels instead of running as one continuous face, and it is easy to lose track of which groove you came down. Take a bearing on the boat, or on the shallow crest overhead, before you start.

The channels are the reason to come. They wind between the coral and open into the caves and arches of the spur-and-groove formation, so navigation is largely a matter of following a groove until it turns and picking up the next one, with the shallow top of the reef always available overhead as a reference on the way back. Nothing on the site goes past about 12 m, which leaves room to work the whole reef in one dive.

Part of the reef lies inside a Sanctuary Preservation Area within the Florida Keys National Marine Sanctuary, and the etiquette is the same as anywhere in the sanctuary: no contact with the coral, nothing taken. That is worth remembering before you enter a swim-through, because a narrow passage is where fins do damage; keep them high and clear of the walls and pass through one diver at a time.