Don’t Play Near the Edge: To scare his teenage daughter on a 1992 trip, a father stood on the guardrail at Grand Canyon National Park, and pretended to lose his balance by windmilling his arms, but actually lost his footing and fell 400 feet to his death.
Don’t Follow Fluffy: A tourist dove headfirst into the scalding 200°F Celestine Pool—one of Yellowstone National Park’s 10,000-odd geothermal features—to try to rescue his friend’s yelping dog in 1981.
Don’t Feed Wild Animals: A boy picnicking with his parents near Yosemite National Park’s Wawona Hotel in 1977 died from a stab wound by sharp antlers after he offered a potato chip to a mule deer.
Don’t Hike in Heels: In order to prevent injuries in Grand Canyon National Park, park rangers at the top of the winding Bright Angel Trail have to remind glamorous tourists that the rocky terrain is a pain for anyone wearing high heels.
This article originally appeared in the May 2015 issue of National Geographic Traveler print magazine.