A Man on a Wire Above China's 'Grand Canyon' The American adventurer Dean Potter "highlining" last weekend in Hubei Province in China. HONG KONG - The best American rock climbers would already seem to have their hands full, from the Gunks and the granite crags in New Hampshire to the Hueco Tanks boulders in Texas, to the storied routes in Yosemite like Half Dome and El Capitan. So what was Dean Potter doing a mile above a canyon in China last weekend? The enigmatic professional climber was highlining, as he and other adventurers call this particular brand of insanity. Mr. Potter, 40, walked barefoot and untethered across some 130 feet of thin, tubular webbing that's essentially a slightly loosened tightrope. He had no safety strap, no parachute, no backup. It was just him, the swaying line, a pair of headphones and the wind. As he has previously said about highlining, "You slip, you die." "The footage is gripping, and to us it looks like he almost loses his balance in several spots," said Rock and Ice magazine in a commentary about the video of the walk, which has now gone viral. But this is just one of the reasons why climbers know him as the Dark Wizard. Mr. Potter has kept a bit quiet about his accomplishment so far, with no interviews yet and no new Twitter messages. (His Twitter profile describes him this way: Artist Adventurer. Best friend of Whisper. Outlaw. Hermit. Goofball. Whisper is his 2-year-old dog.) But after being besieged with requests for what was playing on his headphones, he did post a Facebook message on Thursday: "During my freesolo highline walk in China I listened to Chris Cornell's song, "I am the Highway" off of his Songbook album. For many years now, I hypnotize myself with powerful and emotional tunes, in order to snap into heightened awareness at will. The line was strung above China's so-called Grand Canyon, located in Enshi Prefecture in Hubei Province. As daring and astonishing as it was, and although the height and distance have yet to be confirmed, Mr. Potter's highline seems to have set no particular world record. It was in all likelihood, however, the longest and highest untethered slackline ever completed in China. Whether he was paid by his sponsors or the Chinese government to make the walk remains to be seen. Maybe he just wanted to do something new. Technical climbing, sport and speed climbing, BASE jumping (off high cliffs with bat-winged suits) and other extreme sports are being rapidly established in China. Every major city now has climbing gyms and walls, and hundreds of new climbing routes of increasing difficulty are being "bolted" every year, notably at Liming, in Yunnan Province, and Yangshuo, in Guanxi Province. The Chinese government is actively promoting extreme sports, especially climbing competitions for cash prizes, said Eben Farnworth, a freelance climbing guide in China. "For now the Chinese are more interested in competitions than the enjoyment of the sport for itself," Mr. Farnworth told Rendezvous in a phone interview from his base at Yangshuo. His blog is here, and he recommends climbdali.com as a good online resource for information on sites, outfitters and travel. And it wouldn't be China without some copycatting: A prominent maker of climbing gear, Petzl, based in Utah, has discovered counterfeit equipment in China bearing its logo. Some climbers and adventurers view untethered highlining as foolhardy, similar to "free solo" climbs that are done on difficult rock walls without any safety ropes or backup - just a lone climber with sticky-rubber shoes and a bag of chalk to dry the hands. As a commenter named Kaciak said on Rock and Ice: "I admire his skills, but this particular accomplishment borders with stupidity. Again, I admire your skills Dean but . . . "As an aerialist - Dean's term - he's creating these fleeting visions of senseless, useless, dangerous, and transcendent wonder," Katie Ives, the editor of Alpinist magazine, told Outside magazine in a definitive profile of Mr. Potter last year. Dean wants to shock people out of their routines and preconceptions, to get them to feel the wildness of the world again. In a brief video interview about how and why he slacklines at such dangerous heights, Mr. Potter acknowledged that "it's really uncomfortable and scary to step out on the line." Mostly I'm driven, possessed to do it. But still I'm very scared and I have to force myself out there and hope I enter into the groove quickly. Mr. Potter is widely acclaimed as one of the top climbers in the United States, if not the world, along with Steph Davis (his ex-wife), Chris Sharma, Alex Honnold and the French star Catherine Destivelle. Despite its free-spirited adherents, the professional climbing community can be contentious and highly competitive. There is a scrupulous keeping of rankings, ratings, records and "firsts," and Mr. Potter has his share of detractors. In 2006 he climbed Delicate Arch, the rounded 60-foot formation that is an iconic symbol in Utah. But he lost some respect among fellow climbers - and two major sponsorships - when some observers found that his ropes had cut grooves into the soft sandstone. Mr. Potter vehemently denies he injured Delicate Arch. "On any rock around the world, if I hurt the rock I feel like I'm hurting myself," he said in an interview about the scandal. He has previously spoken about an addiction to high-risk climbing, calling it his "enslavement." "The worst part of Delicate Arch was that Steph lost her job over it, as well," Mr. Potter said, noting that Ms. Davis, who was then still his wife, had not been involved in the climb. Still, he said, it was "the beginning of the end of our relationship" of 13 years. Asked if he would do the climb again, even knowing the consequences to his reputation and his marriage, he said, "I guess that's the messed-up thing about me, but I probably would."