NIAGARA FALLS, Ontario (AP) _ A U.S. stuntman was missing Tuesday after going over Niagara Falls in a kayak, Canadian police said.

The red kayak was recovered below Horseshoe Falls on the Canadian side, ''all in one piece ... in fairly good condition, all things considered,'' said Maureen Quinn, a constable with the Niagara Parks Police. But she said authorities ''found nothing else, just the kayak. No body's been found.''

The Canadian falls, the world's largest by volume, are 181 feet high, or about as tall as a 13-story building.

Another constable, Kim Davis, said the 28-year-old man from Tennessee was trying to complete a stunt that had been planned for about 10 years. Police said nobody has ever tried to kayak over the Canadian side of the falls.

''Barrels, yes,'' said Quinn of other attempts to go over the falls in enclosed capsules and live. But, she said, ''it doesn't seem plausible he could do it (and survive).''

George Bailey of the Niagara Parks Commission said the man had attempted the stunt several years ago on the American side of the falls, but park police stopped him.

He said the man was accompanied by a film crew and a friend who took photographs.

Quinn said police received a call that the stuntman had entered the water about a half-mile above the falls but ''by the time we responded it was too late. ... (He) actually went over the brink.''

She said ''several people saw him go over. It was videotaped. There were plenty of witnesses.''

The man, whose identity was not disclosed pending notification of next of kin, was last seen at about 1:45 p.m. EDT, Quinn said.

Ken Kitchen was working in an Ontario Hydro tower overlooking the Niagara River when he saw a man stripped to the waist in a kayak.

He said the utility closed the dam gates, reducing the water flow to the falls in an attempt to stop him.

The man's boat grounded, but he picked it up and moved it into the middle of the river, Kitchen said.

''He was gone before our help could get there. All we could do was sit and watch helplessly,'' Kitchen said.

At a press conference later Tuesday, police showed reporters a videotape a tourist made of the incident.

The film shows a man in a kayak successfully negotiating the rapids of the Niagara River just before the falls. Then, he disappears.

''It's beyond me why anyone would attempt this,'' said George Bailey of the Niagara Parks Commission. ''He obviously doesn't know our falls.''

Dave Munday, who went over the falls in a steel barrel three years ago, said people who try such stunts are usually not aware of the dangers of the falls.

''A lot of people underestimate what's at the bottom,'' he said. ''I did myself. It's just solid rock down there. People don't realize that.''

Bailey said 13 people have intentionally gone over the falls - most in barrel-like structures. Ten of the 13 survived.