Aleh Kalman, 19, of Sacramento visited the park with a church group Saturday, and went swimming in the Merced River about 150 feet upstream of the waterfall, park spokeswoman Kari Cobb said.
Witnesses said the river's current sent Kalman downstream and over the nearly 600-foot waterfall.
Ground teams of rescuers, three dog teams and a police helicopter searched for his body Saturday and Sunday, and returned Monday, USA Today reported.
"We believe it's impossible to survive a fall like that," Cobb said.
Kalman's presumed death would be the seventh drowning in the park in two years, the newspaper said.
Swim Week Miami Beach 2014 [PHOTOS]