First EVER Hot Air Balloon Flight UNDERGROUND!

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.