The most visited and most photographed slot canyon--a crevice etched out of Navajo sandstone--in the Southwest is Antelope Canyon Navajo Tribal Park, just a few miles from Page, Arizona.
The park is actually comprised of two separate slots, designated Upper, The Crack or The Corkscrew, and Lower.
The swirling 
stones framing the slots stretch more than 100 feet into the air. Their breathtaking hues change from yellow to orange to pink to rust depending on the angle of light beams shining into the canyon. While making for spectacular photography, it is a challenge to keep up with the changing light.
The Upper slot is the most popular, mainly because it has a ground level entrance and the stream bed is flat running through it. At one time, visitors had to navigate ladders to access the 
Lower, but now metal stairways have been installed.
Flash floods mainly carved Antelope Canyon, and they still roar through the wide chambers and narrow passageways today. While the drainage used to be into the Colorado River, it is now into Lake Powell.
Permits are required for both slots, and Navajo guides must accompany visitors.
