One of the best known hikes in Yosemite is the extremely challenging hike up Half Dome. Half Dome is a massive granite dome shaped (who knew) structure clearly visible from the Valley. We have never hiked Half Dome for three reasons; it is hard to get a permit, we are concerned about our level of fitness and I suffer with mild vertigo. The last piece of the hike involves getting up an almost sheer 440ft granite slope. You have to grip onto a steel cable to get to the top and the whole idea makes me feel quite queasy just thinking about it.

If you are sufficiently hard core to give it a go you will need a permit, even to do a day hike. You can try and obtain a permit through entering either the pre-season lottery before you travel or by entering a daily lottery on arrival. The Park Service website has further information

http://www.nps.gov/yose/planyourvisit/hdpermits.htm

Assuming you do manage to get a permit you will be walking for 14-16 miles and will ascend 4,800ft. The Park Service has to rescue many inexperienced / underprepared hikers from Half Dome every year. Please do not become one of them and make sure you read all the material the Service provides to help you enjoy your trip. Good luck!

http://www.nps.gov/yose/planyourvisit/halfdome.htm