Tank Cave, Tantanoola (CDAA-owned, Advanced Cave rating, permit)
Tank Cave is owned and managed by the Cave Divers Association of Australia, and access is limited to divers with advanced cave certification and a controlled permit. CDAA lists it as Advanced Cave rated; it has over 7 km of diveable passage, making it one of Australia's longest underwater caves. A cave diver died there on 30 November 2025; police reported no further safety concerns. Depth is not published on the pages checked.
Facts
- Region: Australia – Mount Gambier Sinkholes & Caves
- Area: Lower South East sinkholes & caves
- Level: advanced
- Current: moderate
- Type: cave, freshwater
- Coordinates: -37.734, 140.5362 (approximate)
- Highlights: over 7 km of diveable passage (CDAA), owned by the CDAA, connects to the Green Waterhole system (news reports, about 10 km)
- Permit: CDAA controlled permit; Advanced Cave rating; visitors via CDAA 3-month Visitor Diving Permit.
- Issuer / contact: Cave Divers Association of Australia (CDAA)
- Website: https://www.cavedivers.com.au
- Tips: CDAA members only, Advanced Cave rating. Certified cave divers can apply for a 3-month CDAA Visitor Diving Permit. Entrance has a restriction. Coordinate is the OpenStreetMap cave-entrance point near Tantanoola, approximate.