Ten Eighty is a large sinkhole in the Mount Schank field described by the CDAA as having two passages at opposite ends, algae in shallow water and excellent visibility at depth. It is graded Basic Cave and owned by Scotts Agencies Pty Ltd, and it is listed as currently closed, along with the same owner's Black Hole and Bullock Hole.

The name is thought to derive from the '1080' pest poison once used in the area, though no source consulted confirms it. Like most of the region's sinkholes, the site is a collapse doline in the Gambier limestone intersecting the water table, so the water is groundwater at a constant 14-15°C. The shallow layer grows algae in the sunlit summer months, which makes the first few metres green and murky; below that the water clears dramatically, and the two passages leading off at opposite ends give the sinkhole a more cave-like character than the simple bowls of Goulden's or Little Blue. Those passages are overhead environments and would be off-limits to Basic Cave divers, who must stay within the daylight zone.

With the site closed, there is nothing to plan beyond keeping it on the watch-list. It is included here because it appears in older site lists and on the CDAA register, and divers researching the region should know it is not currently available. If reopened, it would suit CDAA Basic Cave divers wanting a clear, deeper sinkhole with interesting features to look at from the daylight zone. As with all closed private sites, entering without permission risks further closures across the region.

Ten Eighty is on private land owned by Scotts Agencies Pty Ltd in the Mount Schank area, about 15-20 minutes south of Mount Gambier. The CDAA lists it as currently closed, so no booking, key or access route is available. Do not approach the property without permission; any reopening would be announced via the CDAA dive-sites page with directions, parking and conditions.

Unaffected by swell or tide – the limiting factors are access and surface conditions on private farmland. Summer brings heat, snakes and (at some sites) aggressive bees; Total Fire Ban days can close forestry and some private sites and ban compressors; winter rain turns paddock tracks muddy. Shallow water in sinkholes grows algae in summer, reducing visibility in the top few metres; the water below the thermocline is usually clearer and a constant ~15°C.

Currently closed regardless of conditions.

Not applicable while closed. Historically a Basic Cave dive in the open sinkhole; the end passages are overhead and beyond Basic Cave limits.

CDAA grade: Basic Cave (5L42), owner Scotts Agencies Pty Ltd – currently closed. Passages would require Cave/Advanced Cave grade.

None – site closed (CDAA).