Meet the site
Daniel Roux Cave is one of the best known of Christmas Island's many limestone caves, and one of the few that joins land and sea. On land, Upper Daniel Roux Cave is the island's most accessible dry cave, with glistening shawls, stalactites, stalagmites, helictites and pools, and a colony of Christmas Island glossy swiftlets nesting in the upper chamber. Below it, the system continues down to sea level, where a scientific survey of the island's submarine caves (Tan et al., Raffles Bulletin of Zoology, 2014) recorded two openings in the cliff just south of Smith Point: an upper mouth at 2–3 m and a lower mouth at about 7 m, plus an anchialine pool inside with an obvious thermocline and halocline where fresh groundwater floats on seawater.
For divers this is a cavern dive rather than a penetration dive. With a guide, you enter the lower mouth and explore the daylight zone, where the walls are encrusted with sponges and cup corals and the floor is a mix of sand and rubble. Eels are resident – the researchers recorded freshwater eels (Anguilla bicolor) and uniform moray – along with sleeper gobies in the brackish parts, and cave shrimps glint in torchlight. Outside, the coral slope and wall of the north coast offer the usual Christmas Island reef life for the second half of the dive.
The site matters as a window onto the island's hidden karst world: Christmas Island's anchialine caves hold endemic crustaceans found nowhere else, and Daniel Roux is one of the few places the connection between the land caves and the sea can be seen by a recreational diver. It suits divers comfortable with overhead environments who want something different from the walls, and should only be dived with an operator who knows the cave.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Daniel Roux Cave is recorded as Cave/Cavern in Christmas Island. The listed access is boat. Confirm the actual meeting point, route and permission to visit; a map pin does not establish any of these.
Topics flagged by the stored research
These are questions prompted by the existing notes, not a verified or complete hazard assessment.
- Other water users
- Ask about vessel activity, exclusion areas and the agreed surface arrangements.
- Lines and obstructions
- Discuss any known entanglement concerns and the suitability of the planned area.
- Water movement
- Ask how swell and local exposure affect the proposed entry, exit and route.
- Overhead environments
- Ask whether the plan stays entirely in open water. A wreck or cave listing is not permission or training to enter.
Historical access notes exist for this record, but have not been independently verified for current use. Request current directions from the operator or site manager rather than following an old entry description.
Questions, answered
Is Daniel Roux Cave suitable for my certification?
The record lists Advanced Open Water. That does not establish suitability for every route or day. Share your training, recent experience and equipment needs with the operator and ask about the specific proposed dive.
Can I book Daniel Roux Cave through YouDive?
YouDive is an independent research directory. Contact an operator directly to confirm whether it currently runs the trip, the inclusions and the booking terms.
What you might see
Freshwater eels (Anguilla bicolor), uniform moray (Echidna unicolor), sleeper gobies (Eleotris fusca), cave shrimps, sponges and cup corals; Christmas Island glossy swiftlets in the upper land cave; usual north-coast reef fish outside
Location
Submarine cave with upper (2–3 m) and lower (7 m) sea entrances just south of Smith Point, connecting to an anchialine pool and the dry Upper Daniel Roux Cave on land.
Facilities nearby
Departs Flying Fish Cove jetty/ramp.
Before you make plans
Conditions, access and operator schedules can change. This is a location guide, not a dive plan. Ask a local operator about current conditions and suitability for your training and experience.
Sources & further reading
lkcnhm.nus.edu.sgdivingchristmas.comcuriouscampers.com.auaustraliangeographic.com.auRecord updated 27 Sept 2026. Source claims are being reviewed.