Dive slate · divesites.com.au · printed 8 Nov 2026
Hann's Cave
Mount Gambier Sinkholes & Caves, South Australia · near Mount Gambier
| Depth | Depth not published |
|---|---|
| Minimum level | Cave/Cavern certification |
| Difficulty | Expert/Technical |
| Access | Shore |
| Entry | Unknown – site closed |
| Current | None |
| Water | summer 14-15 °C, winter 14-15 °C |
| Suit | Drysuit strongly recommended (constant ~14-15°C groundwater, long dives); 7 mm wetsuit with hood minimum for short dives |
| Best season | Year-round (constant groundwater temperature); summer/autumn gives warmer surface intervals; forestry sites close on Total Fire Ban days |
| Position | not published |
| Permit | Private land – closed |
| Nearest chamber | Royal Adelaide Hospital hyperbaric medicine unit (Adelaide) – about 450 km by road from Mount Gambier; evacuation is normally by aeromedical retrieval (RFDS/MedSTAR) via Mount Gambier Hospital. The Alfred (Melbourne) is a similar distance. DAN/Divers Emergency Service 1800 088 200. |
| Emergency | 000 · DAN Asia-Pacific diving emergency 1800 088 200 |
Hann's Cave
Also known as Hanns Cave
An Advanced Cave site on the CDAA register – closed at present.
Near Mount Gambier · Mount Gambier Sinkholes & Caves, South Australia
- Depth
- Depth not published
- Minimum level
- Cave/Cavern certification
- Access
- Shore
- Boat ride
- —
- Water
- 14-15 °C
- Visibility
- —
Hann's CaveDepth not published · Cave/Cavern certification · Shore
Dive factsDepths, conditions, location & safety
Season
In season nowBest months: year-round.
Year-round (constant groundwater temperature); summer/autumn gives warmer surface intervals; forestry sites close on Total Fire Ban days
- Best months
- Now (November)
Dive facts
- Depth
- Depth not published
- Certification
- Cave/Cavern certification
- Difficulty
- Expert/Technical
- Access
- Shore
- Dive centre needed
- Yes – permit/guide required
- Shore / independent
- No
- Current
- None
- Water temp (summer)
- 14-15 °C
- Water temp (winter)
- 14-15 °C
- Water
- Cold Freshwater
- Dive traffic
- Rarely dived (private boat/club only)
- Night dive
- No
- Snorkel friendly
- No
Exposure suit
Drysuit strongly recommended (constant ~14-15°C groundwater, long dives); 7 mm wetsuit with hood minimum for short dives
Location
Mount Gambier district · Limestone Coast – Mount Gambier sinkholes & caves
No published coordinates. The map above shows the general area, estimated from other documented sites near Mount Gambier.
Primary source: cavedivers.com.auMarine park & permits
Private land – closed
Nearest recompression chamber
Royal Adelaide Hospital hyperbaric medicine unit (Adelaide) – about 450 km by road from Mount Gambier; evacuation is normally by aeromedical retrieval (RFDS/MedSTAR) via Mount Gambier Hospital. The Alfred (Melbourne) is a similar distance. DAN/Divers Emergency Service 1800 088 200.
Diving emergency: call 000, then DAN AP 1800 088 200.
Trip planner
Build a trip around Hann's Cave →
A day-by-day plan for Mount Gambier Sinkholes & Caves with this site locked in.
This guide is a planning aid. Conditions change daily — confirm with a local dive centre and dive within your training. Data & safety notes.
Dive profile
How this site rates
Scores are computed from the recorded data, not opinions. How?
At a glance
Hann's Cave is a cave / cavern dive in Mount Gambier Sinkholes & Caves, SA, suited to Cave/Cavern certification divers.
Rated expert/technical because of an overhead environment, cold water.
Why dive here
- An Advanced Cave site on the CDAA register – closed at present.
- Rarely dived: expect to have the site to yourself, and plan your own logistics.
About Hann's Cave
Hann's Cave is on the CDAA register as an Advanced Cave site owned by Pedra Branca Dairying and marked 'site is currently CLOSED'.
The Advanced Cave grade is the most useful fact available. Under the CDAA system, Advanced Cave (formerly 'Penetration') sites involve unrestricted penetration, often with restrictions, complex navigation or significant distance from open water; divers must hold the Advanced Cave rating, and many such sites demand sidemount or low-profile configurations, jump reels and strict gas rules. In the Mount Gambier area the Advanced Cave list includes Tank Cave, Iddlebiddy, Stinging Nettle, the Three Sisters, Engelbrecht West and the East Extension, and Hann's belongs in that company.
The same owner's Hancocks Cave – a large cenote reached through a solution tube – is also closed, which suggests the closure relates to access arrangements on that property rather than to either cave specifically. The row is kept so that the database reflects the full CDAA register and so divers do not waste time searching for a site that cannot be dived. If it reopens it will suit experienced Advanced Cave divers. Divers seeking Advanced Cave experience in the meantime have a wide choice of open sites, with Tank Cave, Iddlebiddy and the Three Sisters all bookable through CDAA and ForestrySA systems, and the CDAA site officers are the right contact for questions about Pedra Branca access.
Getting there & entry
An Advanced Cave site on Pedra Branca Dairying land near Mount Gambier; currently closed.
Hann's Cave is on land owned by Pedra Branca Dairying near Mount Gambier (the same owner as Hancocks Cave). The CDAA lists it as currently closed and publishes no directions or booking method. Do not approach the property; any reopening will be advertised through the CDAA site list with access conditions.
Alternative open Advanced Cave sites nearby include Tank Cave and Iddlebiddy.
Entry: Unknown – site closed
Weather, swell & tides
Unaffected by swell or tide. Access and surface conditions on private farmland are the limiting factors: Total Fire Ban days may restrict access or compressors, summer heat makes vertical exits hard work, snakes are active in warm weather and winter rain turns farm tracks muddy. Underwater conditions are stable, with groundwater at a constant ~15°C.
Closed regardless of conditions.
Best season: Year-round (constant groundwater temperature); summer/autumn gives warmer surface intervals; forestry sites close on Total Fire Ban days
How the dive is usually run
Not applicable while closed.
Marine life
- Not documented
Linked species have their own page listing every site where they are recorded. All marine life →
Training required
Courses that help here
- Cavern Diver – An overhead environment.
- Drysuit Diver – Cold water; locals dive dry for much of the year.
Depth tiers: 0–10 m easy · to 18 m Open Water · 18–30 m Advanced (25 m+ is a deep dive) · 30–40 m Deep specialty · 40 m+ technical. All courses
Hazards & warnings
CLOSED – no access.
Technical notes
CDAA grade: Advanced Cave – owner Pedra Branca Dairying; currently closed.
Dive centres that go here
None – site closed (CDAA).
Other dive centres in Mount Gambier Sinkholes & Caves
Dive Experience
ProfiledMount Gambier · Mount Gambier Sinkholes & Caves · SA
A Mount Gambier business serving the region's cave and sinkhole diving community, including equipment and gas support.
dive-experience.com.au · 0478 693 760
Diving Adelaide
ListedMarleston · Adelaide Metro · SA
An Adelaide training and guided diving operation serving local sites and organised trips.
divingadelaide.com.au · (08) 8122 5003
Deep Blue Ventures
Named by sitesMcCrae · Mount Gambier Sinkholes & Caves · SA
Victoria-based technical/cave training operator running Mount Gambier courses (Kilsby-approved).
deepblueventures.com.au · 0413 429 533
Total Immersion Diving
Named by sitesMount Gambier Sinkholes & Caves · SA
Kilsby Sinkhole approved operator running CDAA cave courses in Mount Gambier; Facebook-only presence.
Reef 2 Ridge
Reported closedMount Gambier · Mount Gambier Sinkholes & Caves · SA
TripAdvisor marks it temporarily closed until further notice with the last review in 2018; the SDFSA directory lists only Dive Experience for Mount Gambier.
General area
No position has been published for Hann's Cave. The circle shows where it is likely to be, worked out from other documented sites near Mount Gambier. Ask a local operator for the exact site.
Dashed circle: general area (about 24 km), from other documented sites near Mount Gambier. 6 pinned sites. Pins marked approximate on their pages show the general area only; not for navigation.
Hann's Cave: frequently asked questions
What certification do I need to dive Hann's Cave?
Cave/Cavern certification is the recommended minimum. Rated expert/technical because of an overhead environment, cold water.
Can I shore dive Hann's Cave?
No, it is reached by boat. A dive centre is required: permit/guide required.
When is the best time to dive Hann's Cave?
Year-round (constant groundwater temperature); summer/autumn gives warmer surface intervals; forestry sites close on Total Fire Ban days.
What marine life will I see at Hann's Cave?
Regularly recorded: Not documented.
What wetsuit do I need at Hann's Cave?
Drysuit strongly recommended (constant ~14-15°C groundwater, long dives); 7 mm wetsuit with hood minimum for short dives.
How cold is the water at Hann's Cave?
Typically 14-15 °C in summer and 14-15 °C in winter.
What are the main hazards at Hann's Cave?
CLOSED – no access. See the hazards section above for the full list.
Where is the nearest recompression chamber to Hann's Cave?
Royal Adelaide Hospital hyperbaric medicine unit (Adelaide) – about 450 km by road from Mount Gambier; evacuation is normally by aeromedical retrieval (RFDS/MedSTAR) via Mount Gambier Hospital. The Alfred (Melbourne) is a similar distance. DAN/Divers Emergency Service 1800 088 200. In an emergency call 000, then DAN Asia-Pacific on 1800 088 200.
Diving in Mount Gambier Sinkholes & Caves
The limestone around Mount Gambier is riddled with water-filled sinkholes and caves, and they are the heart of Australian cave diving. Kilsby Sinkhole (65 m, clear as air), the Shaft (124 m), Piccaninnie Ponds' Chasm and Cathedral, Ewens Ponds' spring-fed creek, and the Tank Cave system with more than 8 km of passage. Most sites require Cave Divers Association of Australia rating; Kilsby and Ewens are open to recreational divers by booking.
Getting there: Five hours south-east of Adelaide or four from Melbourne. Sites are on private farmland or in national parks; all need bookings, some need guides.
All Mount Gambier Sinkholes & Caves dive sites and a suggested itinerary →
Sources
- cavedivers.com.au/index.cfm?leca=1831&module=BUSINESSDIRECTORY&pageMode=indiv&action=details&page_id=1404680
- cavedivers.com.au/dive-sites
Data confidence: Low · Being verified: No description, depth or location published.. Last updated September 2026. Know this site better? How to send a correction
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