What is one danger tourists should be aware of when visiting the canyon?

A Extreme cold
B Coyotes
C Flash floods

When the rains come to northern Arizona, they come with a vengeance. Monsoon-like rains, and the flash floods they cause, carved the Navajo sandstone of Antelope Canyon. So when it rains here, no one is allowed into the canyon, as flooding is a serious threat to anyone caught in the rushing waters.

The correct answer is Flash floods.