The sheer rock face in Yosemite National Park that James Kirk free-climbed during shore leave in 2287, falling from it before Spock caught him.
El Capitan is a granite monolith in Yosemite National Park on Earth, seen at the start of Star Trek V: The Final Frontier.
While the new Enterprise-A is being repaired, Kirk spends his leave climbing the cliff without ropes as McCoy watches anxiously through binoculars. Spock floats up beside him on levitation boots to ask why he is doing it, and the distraction makes Kirk lose his grip.
Spock dives after him and catches him by the ankle just above the ground. That evening by the campfire Kirk says he knew he would not die because his two friends were with him.