Christmas Island · Australia · Cave & cavern · Reef · Wall
Thundercliff Cave
A cavern that surfaces in a chamber open to the sky
Area photo: David Stanley from Nanaimo, Canada · CC BY 2.0
Thundercliff stacks the island's three habitats into one profile: reef, then wall, then a cavern that runs back into the limestone and surfaces in a chamber open to the sky. The operator lists it at 5 to 22 metres and grades it intermediate, and the fish along the way are cave sweepers, hammerheads and barracuda.
Where it is and how deep
No published position for this site — the map shows Christmas Island and its other sites; operators know the mooring.
The dive
The outside of the dive comes first. You work the reef and the drop-off, which is where the big fish are: schools of barracuda, hammerheads passing along the edge. The operator's profile bottoms out at 22 metres, so the deep part of the dive is done before you go anywhere near the overhead, and cave sweepers school in the darker water where the limestone begins to close over you.
The cave section is what the site is known for. It ends in a chamber large enough to surface in, open to the sky, which is why the operator calls it one of Christmas Island's signature experiences. The shallow end of the graded range, 5 metres, belongs to this part of the dive and to the swim back out, so the return is made with gas to spare. It is still an overhead environment, entered from the water rather than from land.
Marine life and season
- Hammerheads
- Barracuda
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Good | Good | Good | Good | Good | Good | Good | Fair | Fair | Prime | Prime | Prime |
Season follows Christmas Island: October to December brings the clearest water; August and September bring upwellings and lower visibility; from November to April swell can roughen the north side.
Know before you go
- An overhead environment: the way out is the way you came in, so dive it with a guide who knows the cave and carry a light and a reserve for the return swim.
Questions divers ask
How deep is Thundercliff Cave?+
The operator lists the dive at 5 to 22 metres and grades it intermediate. The deep part is the reef and wall outside; the cavern running back into the island, and the chamber you surface in, sit at the shallow end of that range.
Can you surface inside Thundercliff Cave?+
Yes. The cave ends in a chamber large enough to surface in, open to the sky, and the operator lists it as one of the island's signature experiences. It is reached through an overhead section on a boat dive rather than entered from land.
Sources
- Dive Sites Christmas Island — Extra Divers Australia
In The Logbook
- Cavern and cenote diving without cave trainingCaves & caverns · 8 min read
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