Over the weekend, a group of cavers in Tasmania uncovered the deepest known cave in Australia and dubbed it ‘Delta Variant’. 

Introducing Delta Variant

The newly discovered cave comes in at a depth of 401 vertical metres, four metres deeper than the previous record holder (and next door neighbour) Niggly Cave. The depth of a cave is measured from the highest entrance to the lowest known point. Both Delta Variant and Niggly Cave are connected by the same Niggly/Growling Swallet cave system in Mount Field National Park, north-west of Hobart

The features of the cave have been named after events of the Covid-19 pandemic to remind future cavers of the contemporary events happening at the time (and some of them are pretty damn on point).



The team of nine expert cavers from Southern Tasmanian Caverneers spent over 14 hours underground to reach the bottom of the Delta Variant cave and confirm the depth, entering the mouth of the cave around 11am on Saturday morning and not emerging until 1:30am Sunday morning. 


Photo by Jemma Herbert


‘Saturday’s trip involved an hour and a half bushwalk up a hill, then over 14 hours of abseiling, crawling, squeezing, and rope-climbing, then a long walk back down the hill,’ said project organiser and discoverer of the cave, Stephen Fordyce.

‘About 300 vertical metres was descended on ropes, then painstakingly climbed back up again, with heavy packs full of wet, muddy ropes. The longest continuous abseil is 163 metres high. That’s the height of a 53-story building.’ he said. 

Due to recent snowfall on the surface, there was an unexpected excess of water within the cave, which created an added challenge to the descent.

Hidden in Plain Sight

The descent has been in the works for the last six months since the cave was first discovered, ironically only four metres from the mouth of the Niggly Cave and was overlooked for decades.

‘It (the entrance) is up a short, steep cliff, which no one had ever thought to climb. The actual entrance is hidden by thick scrub and fallen logs. It just shows you what the Tasmanian bush can hide,’ said caver Brendan Moore.


The entrance to the Delta Variant cave | Photo by Stephen Fordyce


Preparations for the trip have included exploring side passages and taking multiple trips further and further down the shaft to fix ropes for the final descent. 

‘We’ve kind of always hypothesised that this cave existed because Niggly is this big cave system and it has this waterfall coming in, and for years cavers have been running looking at this waterfall and wondering, “Where has this water been running from?”,’ Ms Anders told ABC News.

The team of cavers say there’s still plenty more to explore in Tasmania’s cave systems and even in the Delta Variant cave itself.


Photo by Stephen Fordyce


Feature photo by Stephen Fordyce