Trailmaster John McKinney pauses on the steep, aptly named Mist Trail to Vernal Falls.

Yosemite’s waterfalls are world-class natural attractions and the trails leading to them offer memorable hiking for hikers from across the nation and around the world. Most hikers understand Yosemite is a National Park not a water park.

Unfortunately a very few hikers do not.

I was saddened to learn that search and rescue workers are attempting to recover the bodies of three hikers that witnesses say fell into the raging Merced River below Yosemite’s famed Vernal Fall on Tuesday afternoon.

Just 24 hours earlier, on Monday afternoon, I hiked to Vernal Falls with my wife and son.

My heart goes out to families of the victims as well as to the horrified onlookers who witnessed the tragedy while my head cannot comprehend the decision of the three to step past the guardrail at the top of the falls.

The Fresno Bee reports that Hormiz David, 22, and Ramina Badal, 21, both of Modesto, and Ninos Yacoub, 27, of Turlock stepped past the protective guardrail at the top of the waterfall, onlookers said. Eyewitnesses say other visitors pleaded with them to come out of the water, but one of them slipped, starting a chain-reaction and causing the other two, who tried to help, to slip as well.

Vernal Fall is a cascade of uncommon beauty—a 317-foot Merced River spill that plunges over bold granite cliffs. Mist billows from the crashing water, rainbows arch toward the heavens.

And Vernal Fall and the turbulent Merced River can be deadly to park-goers who fail to heed park warnings to stay behind safety railings.

It\’s slippery going along the Merced River.

Ordinarily I avoid the heavy crowds and severe traffic congestion characteristic of Yosemite Valley in mid-summer, but I knew that this year’s record snowfall had created awesome waterfalls. My teenaged son has hiked with me all over Yosemite, but we had never visited the national park when the waterfalls were at full throttle.

Mist Trail is a memorably steep ascent on a stair-stepped trail. En route hikers are bathed in the considerable spray of Vernal Fall.

Vernal Fall was a spectacular sight, and so was another Merced River-fed creation, 594-foot Nevada Fall, which resembled an avalanche of snow.

The trail was jammed hikers, a significant number of them visitors from abroad. I was rather impressed by the number of hikers wearing hiking boots and day packs and actually looking like they belonged on the trail. I was also impressed by the courtesy shown by both fast hikers and slow, and how well behaved the hikers were despite the very heavy foot traffic.

Respect the power of nature by heeding railings and Park signs.

But there are always national park visitors that don’t heed the signs in multiple languages that warn of the danger created by slippery boulders and fast-moving water. On Monday, I watched two twenty-something guys tempt fate by going off trail near the Merced River footbridge located about a quarter-mile above Vernal Fall. They slipped and slid over the rocks but fortunately did not tumble into the raging waters.

My guess is that in Yosemite National Park someone does something that foolish every single day. On Monday afternoon two hikers got away with playing too close to the mighty Merced.

On Tuesday afternoon three hikers did not.

On these busy summer days, some 1,500 people hike up the trail for a look at Vernal Fall. And yet for all the foot traffic to this powerful wonder of nature, casualties are surprisingly few. According to the National Park Service records only 13 people have died by falling over Vernal Fall since records began being kept in the 1920s.

Hiking on a trail is one of the safest activities you can pursue as long as you hike smart—that is to say, plan well, know certain outdoor recreation skills, obey human and natural laws, and use common sense.