Meet the site
Iddlebiddy Cave is an Advanced Cave site in the ForestrySA estate that the CDAA describes, somewhat disarmingly, as a very easy dive for competent cave divers. It consists of a single large passage running south-east for roughly 250 m from the entrance chamber and ending in a small, silty room within a clay deposit. Only a couple of minor areas prevent divers swimming side by side.
The passage is the attraction: long and wide, with large areas of flat ceiling and huge boulders, it gives a sense of scale that many Mount Gambier caves lack. The fragility is the reason for its grade. The cave contains delicate features, especially areas of easily damaged tessellated clay and very soft walls, and the CDAA rules are explicit – do not disturb the entrance debris cone, do not fin or touch the delicate clay blocks, and make all gear adjustments away from the entrance.
Iddlebiddy was first explored in late 1983 and early 1984 and has been open to Advanced Cave members since late 1990. In 1988 human skeletal fragments estimated at around 100 years old were recovered from the entrance debris cone, a reminder that many Mount Gambier holes have histories on land as well as underwater. Depth figures are not published on the listing. It suits Advanced Cave divers who want a long, straightforward and beautiful passage and who can move through it without leaving a trace. Many divers rate it among the most beautiful passages in the region. Photographers value the flat ceilings and boulders, but lighting set-ups must be handled well away from the clay.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Iddlebiddy Cave is recorded as Cave/Cavern in Mount Gambier Sinkholes & Caves. The listed access is shore. 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.
- Lines and obstructions
- Discuss any known entanglement concerns and the suitability of the planned area.
- 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 Iddlebiddy Cave suitable for my certification?
The record lists Cave/Cavern certification. 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 Iddlebiddy 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
Very little – occasional cave crustaceans
Location
A ForestrySA Advanced Cave site with a single large passage running about 250 m south-east from the entrance chamber to a small silty room in a clay deposit.
Facilities nearby
None – forest parking. Fills in Mount Gambier.
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
cavedivers.com.auforestrysa.com.aucavedivers.com.auRecord updated 26 Sept 2026. Source claims are being reviewed.