Exactly ten years after the recording of Felix Baumgartners base-jump in the Mamet Cave went around the World, this abyss on Velebit Mountain became the scene of another daring venture. Ivan Trifonov, a seventy-year-old Austrian with a Croatian passport, was the first man to try, and succeed in flying a hot-air balloon underground. The historic balloon flight – which was inspired by the visionary Jules Verne’s book Journey to the Centre of the Earth – lasted about 25 minutes. Trifonov is experienced hot-air balloon pilot and a proud holder of 4 Guinness records. Flying into the Mamet Cave, touching it’s bottom and successfully flying out of the cave is likely to be his fifth record, since no-one has ever done such a thing before. The aircraft was expertly lowered into the 206-meters deep and 90×160 m wide cave. For flying underground Trifonov had to use a hot-air balloon specially designed for this unusual venture. His balloon was smaller than usual, and the brave pilot set on two gas tanks linked with steel pipes, instead of a basket.
Link to a video.