Frankly, I'm amazed anyone gets out of Yellowstone alive. The national park was the place readers mentioned most often when I invited them to share unsafe tourist behavior they've observed.
Bridget Collins went to Yellowstone in 2002. Like every visitor, she was handed a packet of information when she arrived. On top was a bright orange sheet of paper that read in large type: "THE BISON ARE NOT TAME."
The warning made it clear that any contact with bison was forbidden and laid out every "stupid thing you could imagine some idiot trying to do with a wild animal," Bridget wrote, from feeding it to riding it.
Wrote Collins, of Kensington, Maryland: "I am following another car and we drive further on. [The driver] stops, jumps out of his car, runs across the road and proceeds to take several photos of the sleeping bison on the side of the road. He was three feet away at most.
"I told the ranger later that if the bison had attacked him, I wanted to testify on behalf of the bison."
That man was more fortunate than the teenager Jerry and Michele Sikora of Gaithersburg, Maryland, saw on their visit to Yellowstone. He'd been attacked by a bison after jumping over a fence to pet it.
"The bison gored him and threw him up in the air and he landed on the paved path," Jerry Sikora wrote. "Luckily a nurse was there to help stop the bleeding."
A reader from San Diego named Nancy was at the park in the 1990s, sitting on a boulder above the meadow, enjoying the scenery, if not the sight of a family advancing on a herd of elk for a close-up with their video camera.
"I hear a scream, I look down and see a bull elk with a camcorder hooked on his splendid rack, as he charged the tourists and chased them across the meadow," Nancy wrote. "I felt bad for the animal. I can't imagine having a '90s-era camcorder smacking him in the head was very pleasant."
If the bison and elk don't get you, Yellowstone's geysers might. Thomas Leo Briggs of Rockville, Maryland, watched as a woman stepped off the boardwalk to pose on the steaming ground for a photo.
"She was on a crust covering the hot springs below her," he wrote. "That she did not break through the crust is mostly a matter of luck."
If she had, she would have been parboiled.
During a visit to Hoover Dam, Sheri from California noticed signs warning visitors not to climb or sit on the wall separating them from a 700-foot drop. That didn't stop a mother from placing her screaming 5-year-old daughter there for a photo.
Wrote Sheri: "I don't suppose the heavily armed guards at the Hoover Dam are there to protect children from their parents but maybe they should."
Bad parents come in all flavours. Jonathan Grant of Silver Spring, Maryland, was on a steep trail at Rocky Mountain National Park when he spotted a young teen unscrewing the nut from a bolt holding the rail of a protective fence.
He wrote: "His father saw him continue to do this and merely said, 'Stop doing that.' The brat continued to unscrew the bolt and the father said and did nothing again."
It isn't just US parks where people lose their common sense. Pamela from Durham, North Carolina, visited Machu Picchu in Peru, where a craggy, rocky trail twists up a 10,000-foot peak.
"What scared the bejesus out of me was this girl sitting in the lotus position right on the edge of the area near these rocks," she wrote. "When she got tired of the view she stood up - without using her hands . . .. As much as I admired her strength, I almost woofed my cookies because a tiny bit of dizziness or just a wee motion to catch her balance could have had her off the edge."
Dan from Toronto has witnessed his share of dangerous selfies on his travels. "The worst was at Train Street in Hanoi," he wrote.
Tracks run down the centre of the narrow lane, with restaurants, bars and cafes on each side. "As the train comes, the tables and chairs are folded up and the shop owners tell their customers to stand back against the wall," he wrote. Trains barrel past with just inches to spare.
"We saw one young woman having her perfect Instagram photo taken by her boyfriend as a shop owner insistently yelled to get back," he added.
Seconds before the train came through, the shop owner pushed her to safety.
"I'm sure he saved her life," he wrote.
HM Yaple lives in Wyoming - near Yellowstone, actually - and has seen his share of poor behaviour there. But it was a scene involving a married couple at the Grand Canyon that he still chuckles over.
"His wife was leaning over a rim overlook at a dangerous angle," he wrote. "He said, 'Do you want to have dinner or do you want to fall off a cliff?'"
On your next holiday, make the right choice.
The Washington Post
See also: Why Australia is the land of the idiot