One of the deaths came two weeks ago when a 23-year-old man, Ryan Leeder, fell off the front face of Half Dome, which rises nearly 5,000 feet from the valley floor, screaming as he went, something a witness likened to “the sound of a commercial jet near landing.”

Mr. Leeder’s fall is still under investigation, according to park officials, but foul play is not suspected. The death came on the heels of another one at Half Dome in which Hayley LaFlamme, 26, slipped in wet conditions. She fell 600 feet and was pronounced dead at the scene.

Such gruesome, headline-grabbing deaths have not been limited to Yosemite, of course. In late August, the body of a 59-year-old man was discovered in Yellowstone National Park, having been mauled and killed by a grizzly bear.

For all that, national parks officials say that the parks are not more or less dangerous than years past, and that many of the deaths are from more commonplace causes, like car accidents, heart attacks and suicides. Jeffrey Olson, a spokesman for the Park Service, said there had actually been fewer deaths at national parks so far this year — 113 through last week — than in the same period last year. And that is out of some 280 million annual visitors to the national parks.

“It’s a really, really small percentage of people who don’t make it home,” Mr. Olson said, adding that he thought the public was doing a good job of being safe. “We wish they did a little bit better job, of course. But you can trip on the curb at a park in Manhattan.” (True, though falling off a cliff is certainly less likely.)