Mount Gambier · South Australia
Kilsby's Sinkhole
A limestone sinkhole with water so clear the experience is closer to flying than diving.
Kilsby's Sinkhole near Mount Gambier is one of the most striking freshwater dive sites in the world. A collapsed limestone chamber on private farmland opens into water of extraordinary clarity.
The visibility is the point. With clarity that can exceed anything in the ocean, divers hanging mid-water can see the full dimensions of the chamber, and shafts of sunlight through the entrance produce the images the site is known for.
This is a CDAA-governed site, and access is contingent on both the appropriate cave-diving qualification and the landowner's permission. It is not a recreational dive that happens to be deep.
Max depth
65 m
typically 30 m
Access
shore
Current
minimal
Water temp
15–17°C
Level
technical
| Region | Mount Gambier |
|---|---|
| State | South Australia |
| Access | shore |
| Site type | sinkhole, cave |
| Minimum depth | 0 m |
| Typical depth | 30 m |
| Maximum depth | 65 m |
| Current | minimal |
| Visibility | Exceptional — frequently well beyond 30 m |
| Water temperature | Roughly 15–17°C year-round |
| Experience level | advanced, technical |
These are guidance categories, not guarantees. Conditions on the day, and an operator’s own requirements, override any classification here.
- Very little — these are oligotrophic freshwater systems with minimal life, which is part of why the water is so clear.
A standard Open Water, Advanced or Deep certification does not prepare a diver to enter an overhead environment, and the CDAA system exists precisely to enforce that.
Cave diving introduces requirements that follow directly from the loss of direct ascent.
- no direct ascent to the surface
- continuous guideline procedures
- conservative gas reserve rules
- redundant gas and regulators
- redundant lighting
- silt management and propulsion technique
- complex navigation
The water is groundwater filtered through limestone, with almost no suspended organic material and very little biological activity to cloud it.
That same lack of life is why divers describe the experience as otherworldly rather than as a wildlife dive — the attraction is the geology and the light.
Access
- Located on private property; access is by arrangement.
- CDAA qualification at the appropriate category is required.
- Entry is via a platform and ladder into the sinkhole.
- Freshwater means weighting differs from ocean diving.
Hazards
- depth, with the floor well beyond recreational limits
- overhead environment
- no direct ascent from parts of the site
- clarity causing divers to misjudge depth
- cold water over long dives
- the need for full redundancy in gas and light
Operators servicing this site
Businesses documented as regularly diving this site. Only operators we have established a connection for are listed.
Training that is genuinely useful here
Not a list of everything available — the qualifications that actually change what you can do at this site.
Technical background
Related dive sites
Worth reading alongside this one.
Dive sites nearby
Other documented sites within range, nearest first — useful for building a trip rather than a single dive.
Frequently asked questions
How deep is Kilsby's Sinkhole?
Depths range from around 0 metres to roughly 65 metres, with a typical profile around 30 metres. Conditions and route selection change this considerably.
Is Kilsby's Sinkhole suitable for beginners?
It is better approached with experience beyond entry level. Depth, current or exposure make this demanding regardless of what a certification card permits. Discuss your recent diving honestly with the operator rather than relying on certification alone.
How do you get to Kilsby's Sinkhole?
Access is shore based. Located on private property; access is by arrangement.
Is there current at Kilsby's Sinkhole?
Current is recorded as minimal. Conditions vary daily and should be checked close to the day.
What will I see at Kilsby's Sinkhole?
Commonly reported marine life includes Very little — these are oligotrophic freshwater systems with minimal life, which is part of why the water is so clear.. Sightings are never guaranteed.
When is the best time to dive Kilsby's Sinkhole?
Conditions vary through the year. Visibility is exceptional — frequently well beyond 30 m. Check with local operators close to your dates.
Where is Kilsby's Sinkhole?
Kilsby's Sinkhole is in the Mount Gambier region of South Australia.
Last researched: September 2026. Dive businesses change frequently — confirm current services, prices and requirements directly with the operator before booking.