The man was part of an American tour group visiting the famous 250-metre waterfall.
“He has presumably fallen from a height of 20 metres or more,” Glenn Lura from the Southeast Police District told NTB.
The police were informed that the man had fallen into the waterfall at 6:45pm on Sunday afternoon. Rescue personnel were deployed within two hours. to look for the tourist.
As of Monday afternoon, however, the man has not been found despite a considerable search and rescue operation, which has included a helicopter, divers, alpine rescue teams with dogs, the police, fire department and an ambulance.
Conditions at the waterfall are hampering search and rescue efforts, according to the Southern Norway Joint Rescue Coordination Centre.
“There are strong currents and challenging conditions due to sharp drops and slippery rocks,” Hol's chief of police Torstein Seim told NTB, adding that police and rescue crews are still searching along the river banks for the American tourist.