(Reminds me of Journey To The Center Of The Earth)
"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.
This experienced hot-air balloon pilot is already a proud holder of 4 Guinness records, and 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 inspiration of Trifonov's adventure was the famous Jules Verne's visionary book 'Journey to the Center of the Earth'. "
^ I guess I was right. :)