Meet the site
Hells Hole is a big, raw forest sinkhole – the CDAA summary is 'large sinkhole dropping 30 metres to the water; visibility varies, much tree debris'. It lies on ForestrySA land in the pine plantations around Mount Gambier, one of six wet cave sites the forestry agency manages for CDAA divers, and it is as much a rope-work exercise as a dive.
The defining feature is the drop: the water surface lies about 30 m below the rim, so teams need vertical access gear, a plan for lowering cylinders, and the fitness to climb back out afterwards. Once in the water the sinkhole is open to daylight, with walls falling away into water whose clarity changes with season and recent rain. Decades of fallen trees and branches lie in the water and on the floor, creating a jumble of timber that adds atmosphere but also entanglement and silt risk. It feels remote and wild compared with the pontoons and stairways of Kilsby's or Little Blue.
It is a Basic Cave site, meaning divers stay in the daylight zone with no penetration beyond it. Access is through the ForestrySA online booking system with a key from the Mount Gambier Visitor Information Centre, and the forest closes on Total Fire Ban days. It suits experienced, self-sufficient CDAA Basic Cave teams who enjoy vertical access and a less-visited, atmospheric site. Teams usually allow half a day, with at least one person staying topside to manage ropes and cylinders, and the site rewards those who treat the rigging as seriously as the dive itself.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Hells Hole is recorded as Sinkhole/Cenote 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.
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 Hells Hole 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 Hells Hole 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
Little recorded – algae, occasional yabbies and small fish
Location
A large ForestrySA sinkhole in pine forest near Mount Gambier with a 30 m drop from the rim to the water and much tree debris.
Facilities nearby
None – forest track parking only. 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.