Climbing Half Dome in Yosemite is something everyone should do at least once. It's a major commitment and takes several hours over almost a mile climb, but the views of the valley are unparalleled. One of the most intimidating parts is the last climb up the rock shoulder using the cables. In the past there was no limit to the number of people allowed -- and often there was a line on each of the two cables (one line climbing up and one line climbing down, which is much harder, in my opinion). Now the park issues permits to limit the number of people each day. Be sure to call early to get your permit and pack lots of food and water for the hike. And bring your own gloves for the final climb up the cables.