On Saturday, 19-year-old Aleh Kalman went hiking on the Mist Trail with a church group. In the afternoon, he went swimming in the Merced River when he was swept away by the current and taken over the 594-foot Nevada Fall.
The Mist Trail, from the footbridge above Emerald Pool to the top of Nevada Fall, is temporarily closed as ground teams continue searching for Kalman.
"I've known him for, ever since he moved in that would be about freshman year in high school," said friend Bogdan Pishtoy. "He always had a smile on his face, that's what I remember."
Pishtoy said Kalman grew up in a Christian family and had a lot of Christian Friends, Christian surroundings and read the Bible often.
Park spokeswoman Kari Cobb says the river's current was moving very quickly, with a temperature in the low 50's, when Kalman disappeared.
The Associated Press contributed to this report.