Tommy Caldwell may be the best all-around rock climber in the world.

Two years ago, in his most challenging climb, he scaled a 3,000 foot sheer wall in Yosemite National Park that was described as "smooth as alabaster, as steep as a bedroom wall."

Caldwell* has written a memoir called "The Push: A Climber's Journey of Endurance, Risk and Going Beyond Limits."

He was first introduced to hiking when he was still a toddler - his parents used to take him out and change his diapers in snow caves. He was never very good at team sports, but if the big challenge was just surviving physical torment, he could manage. His best sports, apart from climbing, were wrestling and cross-country running.

Caldwell also made his monumental climb of El Capitan's Dawn Wall without half a finger. He cut it off in a carpentry accident years ago.

*No relation to Rob Caldwell