- Ivan Trifonov
- 206 metre(s)
- Croatia (Obrovac)
The deepest underground balloon flight is 206 m (675.85 ft) and was achieved by Ivan Trifonov (Austria) in Mamet Cave, Obrovac, Croatia on 18 September 2014.
Ivan is a ballooning veteran who also holds two more Guinness World Records titles: First balloon flight over the North Pole, and First balloon flight over the South Pole.