Florida Keys · United States · Cave & cavern · Reef
Hardbottom Cave
A swim-through in the French Reef protected area
Area photo: NOAA (Maya Walton) · Public domain
A named swim-through on French Reef, about seven miles (11 km) southeast of Key Largo, where the spur-and-groove coral is cut with caves and arches. Depths around the site run between twenty and thirty-five feet, about 6.1 to 10.7 m, so it is usually dived as a feature inside a longer French Reef dive rather than as a destination on its own.
Where it is and how deep
25.0342° N, 80.3527° WPublished position for this site.
The dive
Despite the name this is a swim-through in the reef rather than a cave dive, and it is dived as one feature among the caves and arches that cut French Reef's spur-and-groove coral. Depths around this part of the reef range between twenty feet and thirty-five feet, roughly 6.1 to 10.7 m, which keeps the site inside Open Water limits and leaves plenty of gas for the reef either side of it.
The usual shape of a dive here is to work the reef, go through the passage, and carry on along the coral on the far side rather than turning round inside it. Get buoyancy settled before the entrance rather than fixing it in the passage: this is close quarters, and part of French Reef lies within a Sanctuary Preservation Area, where contact with the coral is exactly what the protection exists to prevent.
Marine life and season
The sources we used don't single out particular species here.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Fair | Fair | Good | Prime | Prime | Prime | Prime | Prime | Good | Good | Good | Fair |
Season follows Florida Keys: Winter cold fronts (December-February) bring choppier seas and cooler water; April-August offers the calmest conditions, though hurricane season runs June-November.
Know before you go
- The swim-through is a confined passage: enter with buoyancy already settled and fins high, and go through one diver at a time rather than as a group.
Questions divers ask
How deep is Hardbottom Cave?+
Depths around this area range between 20 feet and 35 feet, about 6.1 to 10.7 m, so the site is shallow throughout and inside Open Water limits.
Sources
- Hardbottom Cave — Scubago
- French Reef — Wikipedia
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