Transcript for Extreme Climbers Attempt Record-Breaking 3,000-Foot Climb
Generally speaking when people are attempting some crazy, maybe it could kill you stunt on the side of a mountain they take a camera crew along with them and we get to see the footage later. Tonight there 24 guys perched on a cliff above yosemite who are attempting an unprecedented climb and they are documenting it in real times. T.j. Holmes has the video. Reporter: It's being called the climb of the century. On a sheer rock cliff, 3,000 feet above yosemite park, professional climbers are attempting to do what no climber has done before. Free climb one of the toughest routes on Earth using only their hands and feet. Ropes only there to protect them from falling. They are attempting to be the first free climbers to conquer el capitan. The journey could take weeks. It's getting pretty rowdy. Reporter: These makeshift tents seven feet long bolted and suspended from vertical rock. Getting tossed around like a rag doll. I'm on a Porto ledge. These two climbers are using one of these secured to a flat surface. They are having to sleep on one of these for weeks possibly trying to make an impossible climb. I have holes here to try to climb the wall. All they have is a flat surface and using their hands and feet. This was no impulse climb. It's been six years in the making. Caldwell and Jorgensen have planned every step of the way. The last big wall that hadn't been free climbed. When you stand at the base and look up it looks like 3,000 feet of blankness. There's nothing there. It's steep, intimidating. Just looks like there's no way you could climb it. This footage was shot by big up productions, a production company that's been following the climbers throughout their entire yosemite quest for an upcoming documentary. I'm grabbing these minuscule edges, jumping between holds, taking huge falls. There's really an element like, am I going to be able to do this? They set out over a week ago, the production crew following their every move. Today is the day. A lot of the snow melted. That's the hottest part of the day at the hottest part of the route. Feels pretty nice. Climbed all day. Started about 10:00 A.M. We didn't finish until about 10:00 or 11:00 P.M. Tommy and I both felt great. It's been 11 days of hard climbing. Until they reach the top they'll eat, rest and sleep in their makeshift tents. A little tour of our camp setup. Pretty sweet. Right now I'm just lounging. Got my feet up. This is like a little nightstand. I've got my iPad for Reading books. Two sleeping bags. If anyone is curious, this is our breakfast setup. Hard boiled eggs, breakfast sandwich with cream cheese and salmon and cucumber and bell pepper. Pretty good eating up here. They are even getting cell phone reception. Able to post upgrades by solar charging their phones. Fortunate to have good cell phone surface. Solar panels up there to charge their cell phones. Their wives are following their progress back home in Colorado. Rebecca says she's not nervous about the dangers of her husband's perilous attempts. They are a climbing family. Their son even has his own miniature wall. I know what it's like up there. I know the safety systems and how good the gear is and how reliable the ropes and harnesses are. I understand that aspect. I don't have much fear. There's always a chance there could be a freak accident and someone could get injured. But it's pretty unlikely. Grabbing on to total razor blades. And the pitch which I fell on earlier this year is one of the most balancing moves, I Still danger is an absolute constant. Climbing a wall completely vertical and the weather can quickly turn brutal. Really calm. A lot of ice built up. Usually little chunks bounce down. Yesterday there was definite big hunks that like go flying by you. The near freezing temperatures are ideal for gripping the mountains. To keep their fingers in shape, they sand them to remove dead skin and apply lotion several times a day. We're taking a rest day today. I've got to tape two of those three fingers which definitely makes it hard to feel what you are hanging on to. I gave it four all-out Many of us on the ground are questioning why someone would want to go through a climb like this, Rebecca Caldwell says for her husband it's about more than the thrill of the rise. Climbing is definitely not about an adrenaline rsh. It's about focus and being precise and it's about thinking through things. It's really mentally challenging and physically challenging and all of those things together. It's taken a lot of time for Tom my and Kevin to prepare for this and get everything to align and be performing at peak level in all of those areas to accomplish this. As of tonight, Caldwell and Jorgensen are resting at about the halfway point of el capitan. Still about 1500 feet to go. You want to find something that looks absurd and figure out how to do it. This image is the latest update from the mountain today. Kevin Jorgensen halfway to conquering don wall. For "Nightline," I'm T.J. Holmes in New York.
This transcript has been automatically generated and may not be 100% accurate.