In the past 150 years, thousands of people have gone over Niagara Falls. Some of these have been daredevil attempts. Others have been suicides. On average, between 20 and 30 people go over Niagara Falls each year.
Unsurprisingly, going over Niagara Falls (in a barrel, kayak, boat, jet-ski, in a life jacket, or etc.) is illegal and there are consequences for doing so. One of those consequences is a $10,000 fine payable to the Canadian government and up to a $25,000 fine payable to the U.S. government. Another is being banned from entering Canada ever again.
The penalties for going over Niagara Falls only matter if you survive, which more than 50% of daredevils have in recorded history.
FACT: it became illegal to go over Niagara Falls after a failed daredevil stunt in 1951 where William "Red" Hill, Jr. attempted to survive the plunge in a homemade flotation device consisting of 13 truck tire inner tubes.