This page contains information regarding Star Trek: Lower Decks, and thus may contain spoilers.
"And that is?"
"Because it's there."
As a challenge to himself in 2287, James T. Kirk attempted to free climb El Capitan solo, without any safety equipment. It was an attempt which very nearly resulted in Kirk's death after he lost his grip and began to fall. Fortunately, Spock saved the captain's life by using levitation boots to float high enough to catch the captain by his ankle.