The hike to Half Dome is considered a very strenuous and covers 17 miles which takes an estimated time of 10-12 hours to complete.  The total elevation gain is 4800 ft.

 
Follow the Mist Trail or John Muir Trail to Nevada Fall.  Continue on the trail by following the Merced River to Little Yosemite Valley and Half Dome.  The last 900 ft. of trail is a very steep climb up the east side of Half Dome.  Cables assist hikers on the final 400 ft.

  
They consist of two steel ropes about three feet apart and suspended at arm's height from pipes set in the rock.  Do not begin this ascent if 1) the cables are down, 2) there is any chance of rain (moisture makes the granite too slick for safety), or 3) there is any chance of lightning.  Lightning often strikes the Dome's summit and can follow the cables downward.

 
The top of Half Dome is a fairly level, large open surface.