(Reuters) - Park rangers on Wednesday were searching for the body of a man who was presumed dead after falling into a hot spring at Yellowstone National Park in Wyoming, a park spokesman said.
The unidentified man in his early 20s was seen by a witness plunging into the hot spring in Norris Geyser Basin after straying some 225 yards from a wooden boardwalk designed to prevent such accidents, according to park spokesman Neal Herbert.
The National Park Service warns on Yellowstone's official website that hot springs, where water temperatures average 143 degrees Fahrenheit, have injured or killed more people than any other natural feature.
Last month, Yellowstone managers warned visitors to leave wildlife alone after two tourists put a newborn bison calf in their car, touching off a string of events that ultimately led to the animal's death.
Each year some four million people visit Yellowstone, the first national park established in the United States.
(Reporting by Dan Whitcomb; Editing by Alistair Bell)