Yosemite Valley ( yoh-SEM--tee; Yosemite, Miwok for "killer") is a glacial valley in Yosemite National Park in the western Sierra Nevada mountains of Central California. The valley is about 7.5 mi (12.1 km) long and 3,0003,500 ft (9101,070 m) deep, surrounded by high granite summits such as Half Dome and El Capitan, and densely forested with pines. The valley is drained by the Merced River, and a multitude of streams and waterfalls flow into it, including Tenaya, Illilouette, Yosemite and Bridalveil Creeks. Yosemite Falls is the highest waterfall in North America and is a big attraction especially in the spring, when the water flow is at its peak. The valley is renowned for its natural environment and is regarded as the centerpiece of Yosemite National Park.

The valley is the main attraction in the park for the majority of visitors and a bustling hub of activity during tourist season in the summer months. Most visitors enter the valley from roads to the west and pass through the Tunnel View entrance. Visitor facilities are in the center of the valley. There are both hiking trail loops that stay within the valley and trailheads that lead to higher elevations, all of which afford glimpses of the park's many scenic wonders.

Warren Harding (June 18, 1924 – February 27, 2002) was one of the most accomplished and influential American rock climbers of the 1950s to 1970s. He was the leader of the first team to climb El Capitan, Yosemite Valley, in 1958. The route they climbed, known as The Nose, ascends 2,900 feet (880 m) up the central buttress of what is one of the largest granite monoliths in the world. Harding climbed many other first ascents in Yosemite, some 28 in all, as well as making the first true big-wall ascents in the Sierra Nevada range of California.He was nicknamed "Batso", a reference to his remarkable penchant for spending days living on vertical cliffs and his exuberant and iconoclastic character. Harding developed specialized equipment for climbing big walls, such as the "bat tent" for sleeping, and "bat hooks" used to hook precariously on small cut-out bits of granite—examples of his B.A.T. or 'Basically Absurd Technology' products. He was known for his doggedness, drinking, and farcing, as reflected in his motto: Semper Farcisimus!Harding authored the book Downward Bound: A Mad! Guide to Rock Climbing. The book contains a description of the ascent of the Nose and the Wall of Early Morning Light (1970), as well as farcical instruction in climbing basics, ratings of prominent climbers of the period, a humorous account of rock climbing controversies and life-styles of the 1960s and 1970s, and a vivid portrayal of Harding's own rebellious and charismatic character.