At its core are the remains of a magma chamber that cooled slowly and crystallized beneath the Earth's surface.

Although the trend of this ridge, as well as that of Tenaya Canyon, is probably controlled by master joints, 80 percent of the northwest "half" of the original dome may well still be there.

[4] The summit was reached by George Anderson in October 1875, via a route constructed by drilling and placing iron eye bolts into the smooth rock.

[5] Anderson had previously tried a variety of methods, including using pitch from nearby pine trees for extra friction.

After a rigorous 2 mi (3.2 km) approach, including several hundred feet of rock stairs, the final pitch up the peak's steep but somewhat rounded east face is ascended with the aid of a pair of post-mounted steel cables originally constructed close to the Anderson route in 1919.

Alternatively, over a dozen rock climbing routes lead from the valley up Half Dome's vertical northwest face.

The first technical ascent was in 1957 via a route pioneered by Royal Robbins, Mike Sherrick, and Jerry Gallwas, today known as the Regular Northwest Face.

The National Park Service recommends against climbing the route when the cables are down, or when the surface of the rock is wet and slippery.

Hikers caught bypassing the rangers to visit either the sub-dome or main dome without a permit face fines of up to $5,000, and/or 6 months in jail.

Often confused with "the Visor," a small overhanging ledge at the summit, the Diving Board is on the shoulder of Half Dome.

[23] Half Dome was originally called "Tis-sa-ack", meaning Cleft Rock in the language of the local Ahwahnechee people.

Tis-sa-ack is also the name of the fourth route on the formation, ascended by Royal Robbins and Don Peterson over eight days in October 1969.

[41][42][43] Jack London's 1900 short story "Dutch Courage" tells of a fictional climb of Half Dome.

From 2010 until the introduction of REAL ID, California driver's licenses featured an illustration of Half Dome.