Kevin Jorgeson and Tommy Caldwell are free-climbing to the 3,000 foot summit in Yosemite National Park in California.
The pair will be the first to "free climb" El Capitan's Dawn Wall, the tallest granite monolith in the world, using only their hands and feet, ie no ropes, to scale the sheer granite face.
What's even more amazing is that one of the climbers, Tommy, has only nine fingers after he accidentally cut off the index finger on his left hand above the knuckle while using a table saw in 2001.
They only have a rope to catch them when they fall, which they have done many times.
For instance, Jorgeson has fallen 11 times and shredded the skin on his fingers at one part of the wall, and got stuck there for a week as a consequence.