Hike up Lower Antelope Canyon near Page, Arizona.
There are two ways to get to lower antelope canyon. If you want to drive, you'll need to pay for a tour guide to walk you through the narrows. You'll also have to share the view with dozens of your closest friends. Or....
Take your boat from Lake Powell up Antelope canyon until you can't go any further. Park the boat and walk until you're bored. Antelope is one of the most picturesque slot canyons around, so this is an easy but enjoyable walk.
If you liked this, you might want to try Upper Antelope Canyon as well.