The duo broke the Nose record three times in the past week, carving more than 20 minutes off a mark set last year. Honnold said it would have been easy to stop after setting records on Tuesday and May 31, but they pressed towards the two-hour goal he considered the "human potential" for the route.
Hans Florine, who has held the speed record for the climb on and off between 1990 and 2012 — the last time with Honnold — said the new mark is equivalent to the ongoing quest to break the two-hour marathon or Roger Bannister's 1954 achievement in the mile.
"We were pushing the five-hour barrier before and then the four-hour barrier and then the three-hour barrier. So which one of those is the four-minute mile?" Florine said before the mark was broken. "I think it is getting close."
Climbing times on El Cap have fallen precipitously since the first ascent of the cliff 60 years ago by Warren Harding and two others. That milestone took 12 days in a final push that followed 48 days of advance work over 18 months as Harding pounded bolts into the route to aid his climb.
"As I hammered in the last bolt and staggered over the rim, it was not at all clear to me who was the conqueror and who was the conquered," Harding said afterward.
Yosemite is mecca for climbers around the world because of its vast array of beautiful soaring granite walls and peaks. El Cap, though, looms largest and offers 58 distinct routes. The Nose is the best known and typically takes accomplished climbers four or five days.
Climbers jam hands and feet into finger- and fist-width cracks to inch their way up the vertical wall. Ledges large enough to camp on offer respite, but sometimes there is little more to grasp or perch on than a sliver the width of a few coins. Other cracks come abruptly to an end in a sea of smooth granite, forcing climbers to swing 9m left or right to find the next hand or foothold.
"It's a very complicated route," said Daniel Duane, author of the book El Capitan. ''It meanders all over the place and it has pendulum swings and bolt ladders and there are little variations where you can go this way and instead of that way, so there's a tonne of trickery involved in shaving off time."
Speed can come with a devastating price. Climbers are roped together for safety, and they clip their lifeline into protective pieces that they place in cracks along the way to catch them if they fall. But the amount of gear in a race against the clock is pared to the bare minimum to save weight, and climbers sometimes move in tandem with neither anchored to the rock.
The two expert climbers killed at the weekend were speed climbing in that manner on El Cap's Freeblast route when one fell and pulled the other 305m to their deaths.
Last year, Quinn Brett, a former women's speed record holder on the Nose, was trying to improve her time when she took a freefall and slammed a ledge below, leaving her paralysed below the waist.
Caldwell took 18m and 30.5m falls during practice runs but was uninjured, said photographer Austin Siadak, who has been shooting video of the team for a documentary.
"It was pretty scary because it was such a gargantuan fall," Siadak said of the larger fall. "I saw him hurtling upside down through the air and then bouncing on the end of the rope."
But once Caldwell came to a rest, he chalked up his hands, swung over to a crack and resumed his upward progress.
Honnold, 32, and Caldwell, 39, are arguably the biggest stars of rock climbing with multiple accomplishments.
Caldwell and Kevin Jorgeson earned fame in 2015 on the first ascent of El Cap's Dawn Wall, one of the world's hardest routes, using nothing to assist their 19-day climb and only ropes and gear to protect against a fall.
Honnold is the only person to have climbed El Cap solo without a rope or any protection, a perilous feat that earned him widespread praise and also criticism for being reckless.
The two climbers represent a sort of "dream team" from a generation who honed their craft in rock gyms and "are showing up in the outdoors with a radically different ability level than they used to," Duane said.
So even with climbers like Honnold and Caldwell setting new high marks, records are made to be broken.
"At one level it's hard to imagine, gosh, how could anybody get better than those guys?" Duane said. "Yet sports move that way and they keep moving and they never stop moving."
- AP