ABOVE: Watch the incredible footage as Ivan Trifonov pilots a hot air balloon into an underground cave
An Austrian balloon pilot has succeeded in taking a balloon deep underground, a feat which he believes is a world first.
Ivan Trifonov, 70, managed to descend into Mamet Cave, on Velebit Mountain in Croatia, and ascend back above ground, on 18 September.
The cave is 206 metres (675 feet) deep with an opening at the top which is 60 metres (200 feet) wide.
The hot air balloon flight took around 25 minutes to complete, using a balloon especially designed for the stunt.
Instead of a basket Trifinov sat in a small steel frame, perched above twin gas tanks.
The stunt was filmed from multiple angles and is being submitted to the Guinness Book of World records.
“It was very hard and I don’t think anyone else will ever repeat this venture,” he said.
If accepted, the descent into Mamet Cave in a balloon would be Trifonov’s fifth world record.
Amongst other feats, Trifonov has ballooned over the South Pole.
© 2014 The Associated Press