On July 22nd 1976, Soucek attempted to cross the Whirlpool on a moped, also known as a "limited-speed" motorcycle. He planned to cross by using the cables of the Spanish Aero Car. This attempt failed when his moped hit a bolt and was derailed, only 6 m into the trip. A safety harness worn by Soucek saved his life by preventing him falling into the Whirlpool below.
On June 11th 1977, Karel Soucek made a successful trip through the Whirlpool Rapids in a barrel made entirely of steel. In the Whirlpool, Soucek became stranded for three hours. Upon being rescued and returned to shore, Soucek was arrested by the Niagara Parks police and charged with performing a stunt without a license. Even after this fining he completed a second barrel trip through this area.
On July 2nd 1984, Karel Soucek challenged the great Horseshoe Falls in a homemade barrel. The specially designed barrel was made of lightweight metal and plastic. It was also equipped with enough counterweight in one end to ensure a feet first plunge, and a two-way radio. Soucek spent $15,000 to prepare for his journey. He would become the first person to attempt the dangerous journey over the Falls in 23 years. He called himself the “Last of the Niagara Daredevils”.
At around 9:30 a.m., four assistants pushed the barrel with Karel Soucek inside from the back of a truck several hundred yards upstream of the Horseshoe Falls along the Canadian shore, without police interruption. The barrel moved quickly down river and over the Horseshoe Falls at 121 km/h. The counterweight was a success for the 3.2 second trip over the Falls. Soucek later described it as similar to a skydiver's free fall. For 45 minutes the barrel bounced off the rocks at the base of the Falls. Soucek had plenty of oxygen, so he relaxed and awaited release by the changing water currents. When this occurred the barrel was quickly recovered and brought to shore.
It was a dream come true for Soucek and he became the eight person to conquer the Falls. Soucek walked away from the barrel, was lifted to the surface and then taken to the Greater Niagara General Hospital for minor cuts and bruises. Soucek was charged by the police and his barrel confiscated. The Niagara Falls Ontario Provincial Court fined him $500 for the stunt.