Whitmore was part of the group of climbers who were the first to ever scale Yosemite National Park's iconic El Capitan rock wall in 1958.
He died New Year's Day from complications caused by COVID-19.
At the time of his ascent in 1958, climbing the 3,000-foot granite wall in Yosemite was seen as impossible.
Today, it attracts rock climbers from all across the world.
The Fresno native was a long time conservationist, devoting his life to protecting the Sierra Nevada.
He was involved with the Sierra Club and helped establish the Kaiser Wilderness, the California Wilderness Act of 1984 and stopped the Walt Disney Company from building a ski resort at Mineral King.