This incident happened at Nevada Falls.

"Park rangers spent Sunday searching for a teenage swimmer who was swept over a nearly 600-foot waterfall in California's Yosemite National Park over the weekend.

Aleh Kalman had been swimming about 150 feet from the edge of the Nevada Fall on Saturday afternoon when he was caught up in the swift current of the Merced River, the National Park Service reported. The 19-year-old Sacramento resident had gone to the park with a church group, the park service said. "

From the Sacramento Bee: "Officials have closed the trail below the falls while the search continues."

Unfortunately, that that pool above Nevada is particularly still and inviting, but in spring flow, its outlet goes from zero to sixty in about two feet, straight to the fall. The rapids shown in the summer picture linked above hardly show a rock in the spring. Despite the guardrail, people picnic, and obviously dip, along the granite apron right to the outlet.

This photo was taken from the same spot (the bridge), looking immediately downstream.