RMS Rhone & Salt Island · British Virgin Islands · Pinnacle
Thumb Rock
A thumb-shaped rock, mostly inside 15 m, in clear water
Area photo: Gareth Richards · CC BY 3.0
A pinnacle off Cooper Island named for its shape, rising from a base at about 24 metres to within 5 metres of the surface. Most dives stay inside the top 15 metres and circle the rock at more than one depth. It gets passed over for Wreck Alley next door, which is a shame: the water here is usually clear, and spotted drums, seahorses, tarpon and barracuda are all on the rock.
Where it is and how deep
18.3720° N, 64.5150° WApproximate position — the dashed circle shows where the site lies; your operator's briefing has the mooring.
The dive
The pinnacle rises off Cooper Island and takes its name from its shape. It runs from about 24 metres at the base to within 5 metres of the surface, so you can circle it at more than one depth on the same dive, and most dives stay inside the top 15 metres. The water here is usually clear. The catch is the surface, which can be rough enough to make getting in and out the awkward part of the day.
Take the circuit slowly. Spotted drums, seahorses, creole wrasse and lobsters are all found on this shallow rock, with tarpon, French and queen angelfish, filefish and barracuda around it. Current wraps around the pinnacle, so expect a slight push on one side and calm water on the other, and plan the lap accordingly. Because the working depth is shallow, a tank goes a long way here, which is why it fits well after the deeper wrecks a short run away.
Marine life and season
- Barracuda
- Macro critters
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Prime | Prime | Prime | Prime | Good | Good | Good | Fair | Fair | Fair | Good | Prime |
Season follows RMS Rhone & Salt Island: Nov–Jun is calmest and clearest; Aug–Oct hurricane season brings swell that can close the exposed Rhone site entirely.
Know before you go
- The rock is exposed and the surface can be rough, so entries and exits are the awkward part; go on the crew's call rather than swimming to the line in your own time.
Questions divers ask
How deep is Thumb Rock?+
Most of the dive is limited to about 15 metres, though the pinnacle continues down to roughly 24 at its base. The shallow profile gives long bottom times.
Sources
- Diving in the British Virgin Islands — Wikivoyage
- British Virgin Islands Diving Sites — Dive The World
More dive sites in RMS Rhone & Salt Island
A reef the length of Ginger Island's calm north side
Reef
A rocky islet between Ginger and Cooper, sloping to 30 m
Reef
Pillar and black coral at 21 m with pelagics passing through
Overhangs and a gentle slope in 6 to 15 m off Cooper Island
Wreck
Four scuttled hulls on one mooring, from 20 to 27 m
A 5 m (15 ft) propeller and open gearing in 9 m of water
The 1867 liner's forward hull, swum at 24 m
Pinnacle
An amphitheatre of rock, ledges and swim-throughs to 18 m
Similar dives elsewhere
A full circuit of the rock, then up the canyon on its northeast side
Reef sharks circling outcrops that peak at 23 m and fall away below
Tidal pinnacle off Bastimentos with sand channels and schooling fish
Caribbean reef sharks around a lone rock breaking the surface far offshore