A woman lost her footing after stepping over a retaining wall to take a photograph and went over a cliff, falling 500 feet to her death in a canyon, park officials said.
The 52-year-old woman was visiting the park with her husband and two children.
Her husband flagged down a passing motorist, who called 911 after the Saturday morning accident at an overlook along the Yellowstone River, park officials said.
A ranger rappelled down the canyon wall to reach the woman, but she was dead at the scene.
"It's hard for me to articulate right now because I'm still in shock," said Rockford Superintendent Mike Shibler, who said he spoke to Chamberlin's husband, Gary.
It was the second fatal accident in Yellowstone this year. In February, a woman was killed in a snowmobile accident.