This one REALLY Rocks!
This was my second choice, right after Multnomah Falls. You can thank Henry Biddle and Chas Johnson for this hike, because there's no way the trail would be built today. They blasted out portions of the side of this rock back in 1915, and spent four years attaching metal hand rails. This one is not for those with a fear of heights, nor for small children.
Depending on how you define rock, this is the second largest of its kind in the world. It is the remnant of a volcano that erupted around 60,000 years ago.
The parking lot is right next to the highway, and has restrooms. Walk West to the trailhead sign. This is what you'll be climbing. The trail goes about a quarter mile through trees, then starts up the side of the rock to a gate. From here on out it's up, up, and up along metal railing, with so many switchbacks that you'll get a little dizzy. The views get better; here's the view of Bonneville Dam to the East. The view down the gorge to the West is just as impressive. The trail meanders around to the East side of the rock; note that the wind picks up quite a bit here. Here I am at the summit.
As with any free parking lot in this region, be sure to hide and secure your valuables. Another few miles East is the Bridge of the gods, and for $1 you can drive across it to the Oregon side of the river.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.