Antelope Canyon is a slot canyon carved by flash floods through Navajo sandstone, producing walls that curve and swirl in wave-like formations stained in shades of orange, red, and purple. The shafts of light that drop through the narrow opening in the canyon's ceiling and illuminate the sculpted walls — most dramatically around midday in summer — are genuinely unlike anything else in the world.
There are two sections: Upper Antelope Canyon (the Wave, or Tse' bighanilini in Navajo) and Lower Antelope Canyon (the Corkscrew, or Hasdeztwazi). Upper is more famous and more visited; Lower requires some climbing but gets comparatively fewer crowds. Both are on Navajo land and can only be visited on guided tours, which must be booked in advance. For photography, the midday tours in summer get the best light beams.