Hot air balloon flies underground - level 3
A seventy-year-old Austrian adventurer has successfully landed a hot air balloon in a cave 200 meters deep in the Velebit Mountains in Croatia.
Ivan Trifonov, decided to fly down, touch the cave's bottom and fly out of the cave, in a never seen before attempt at flying a hot air balloon underground.
Ivan's mission comes exactly ten years after fellow Austrian adventurer Felix Baumgartner pulled off a parachute base jump on the same spot.
This historical air balloon flight took around 25 minutes, from the initial take-off on surface, through touching the bottom of the cave, and flying out and landing back on surface.
Difficult words: initial (occurring at the beginning), surface (the ground on top of something).