Potter "was the most intense, driven, inspirational climbers in the past two decades," a fellow climber tells PEOPLE

Credit: Wu Hanren/AP

Dean Potter, one of the world’s best-known BASE jumpers and climbers, was killed on Saturday while attempting an aerial flight over Yosemite Valley after jumping off a 7,500-foot overhang.

Potter, 43, and fellow climber Graham Hunt, 29, were reported missing late Saturday night by friends who lost contact with the wingsuit-clad men shortly after they jumped from Taft Point in Yosemite National Park and attempted to navigate their way over an expanse of terrain that involved clearing a notch in a rocky ridge line, according to Outside online.

“Dean was definitely the most intense, driven, inspirational climbers in the past two decades,” climber Chris McNamara tells PEOPLE. “Everything he did was new. He didn’t follow anyone else and was constantly inventing new approaches to experience the outdoors – whether it be slacklining, BASE jumping or climbing.”

Shortly after their leap, a friend reportedly heard a sound that she believed to be either that of a parachute opening or an impact. Potter and Hunt’s bodies were located the next morning by search and rescue personnel from Yosemite National Park and the California Highway Patrol.

BASE jumping – which involves leaping from cliffs or other high man-made structures with the use of skintight wingsuits with batwing sleeves and parachutes – is illegal in Yosemite.

Potter first made headlines in 2006 after he free soloed (climbing without any ropes, harnesses or protective gear) Utah’s iconic Delicate Arch, a controversial climb that led one of his corporate sponsors to drop him. Two years later, he ascended a difficult route up the north face of Switzerland’s 13,020-foot Eiger with little more than a parachute on his back.

Potter also pushed the boundaries of highlining, which involves walking across a rope stretched between two towering rock formations, wearing a parachute in the event of a fall.

Last year, Potter and his goggle-clad dog Whisper, who was strapped to his owner’s back, became online video sensations after footage of the two BASE jumping went viral. The dog was not involved in the fatal jump.

“Everyone in this sport has now seen enough really skilled, careful people die,” observes McNamara, who stopped BASE jumping in 2009 because of the dangers. “There’s just this very thin margin of how things can go from ‘totally fine’ to ‘it’s over.’ And it’s really hard to do this sport a lot and have that margin not catch up with you.”

In an interview last year with Outside magazine, Potter confided that part of what drove him to push the boundaries of extreme sports stemmed from a childhood dream.

“When I was a little boy, my first memory was a flying dream,” Potter said in the video. “In my dream, I flew – and I also fell. I always wondered as I got older if it was some premonition of falling to my death.”