Lafayette Bunnell, a member of the Mariposa Battalion that entered Yosemite Valley in 1851, gave the waterfall its English name. "Vernal" means relating to spring, and Bunnell chose it for the cool, verdant feeling of the spray-soaked grotto at the waterfall's base, which reminded him of a perpetual springtime even in the heat of summer. The Mariposa Battalion was not there to admire scenery - they had come to forcibly relocate the Ahwahneechee people from the valley - but Bunnell was captivated enough to record the falls and their indigenous name. Yan-o-pah captures something the English name does not: the cloud that forms around the base, a permanent weather system created by the impact of water on stone. Vernal Fall flows year-round, though by late summer it thins to multiple strands rather than the single thundering curtain of spring. The difference between May and September is the difference between walking through a storm and admiring a silver thread from a distance.

The Mist Trail begins at the Happy Isles trailhead in Yosemite Valley and climbs 1.3 miles to the top of Vernal Fall - one of the shortest and most popular hikes in the park, but not the easiest. The trail is mostly shaded and gains elevation steadily through pine forest before reaching the base of the falls, where the mist begins. The final stretch is a steep climb up granite steps, the last 15 minutes demanding enough that hikers often stop to rest on the wet rock and watch the water cascade past them at arm's length. At the top, the reward is immediate. The Emerald Pool spreads out above the fall, its green depth fed by the Silver Apron - a 20-degree slope of water-polished granite where the Merced River slides like liquid glass before tipping over the edge. Hikers lounge on the warm rocks around the pool, their exhaustion mixing with the particular satisfaction of having earned a view. The trail continues beyond Vernal Fall to Nevada Fall, 594 feet high, making a strenuous but spectacular loop.

The Emerald Pool and Silver Apron are among the most dangerous places in Yosemite. The rocks above the fall are polished smooth by millennia of water, and the river carries strong undercurrents invisible from the surface. Swimming is illegal and warnings are posted in multiple languages, but the pool's inviting green water and the flat sunbathing rocks draw people in every summer. Several visitors have died after wading into the water and being swept over the 317-foot drop. On July 19, 2011, three people died in a single incident when they were pulled over Vernal Fall after entering the river near the Silver Apron. The current looked gentle from the bank. It was not. The geology that makes Vernal Fall beautiful - the smooth granite, the gentle gradient of the Apron, the way the river seems to slow before the edge - is exactly what makes it deadly. There is no turbulence to warn you, no rough water to signal danger. The river simply slides, and then it falls.

In 1932, the Philippines issued a postage stamp depicting what it labeled Pagsanjan Falls, a famous cascade southeast of Manila. There was a problem: the waterfall on the stamp was not Pagsanjan Falls. It was Vernal Fall, in Yosemite National Park, roughly 7,000 miles away in a different country on a different continent. The engraver had apparently used a reference photograph of Vernal Fall by mistake, and nobody caught the error before the stamps were printed and distributed. The misidentified stamp became a collectors' item and a footnote in both philatelic and Yosemite history. It is a small, strange piece of Vernal Fall's legacy - proof that even in the age before the internet, images of this waterfall traveled far enough to end up on the wrong side of the Pacific, attributed to the wrong country, and printed on millions of small adhesive rectangles that people licked and stuck on envelopes without ever knowing they were looking at California.