New York "Fearless Felix" Baumgartner has jumped 2,500 times from planes and helicopters, as well as some of the highest landmarks and skyscrapers on the planet — the Christ the Redeemer statue overlooking Rio de Janeiro, the Millau Viaduct in southern France, the 101-storey Taipei 101 in Taiwan.
He's also leapt face-first into a pitch-dark, 189 metre-deep cave in Croatia — his most dangerous feat yet, he says, but soon to be outdone.
This summer, Baumgartner hopes to hurtle toward Earth at supersonic speed from a record 37 kilometres up, breaking the sound barrier with only his body.
He made it more than halfway there during a critical dress rehearsal on Thursday, ascending from the New Mexico desert in a helium balloon and jumping from more than 21km up.
The record so far is Air Force test pilot Joe Kittinger's jump from 102,800 feet — 31.3km in 1960.
"I like to challenge myself," Baumgartner, 42, explained in a recent interview, "and this is the ultimate skydive. I think there's nothing bigger than that."