Mary Connors is best known for what she failed to achieve. She repeatedly tried to cross the River Avon by being fired across it in a cannon, and she kept ending up in the river.
She first tried in 1974, and failed three times in a row. When she then tried to cross the river using a rope and pulley, the pulley jammed, sending her once again into the water.
She tried again in 1976. Once again, she ended up swimming. I think, overall, she made five failed attempts, and never succeeded.
Another highlight of her career was that in 1975 she performed the human cannonball act topless, and she did get that right.
You can watch a video of her first failed attempt at crossing the Avon over at the MACE archive (media archive for central England)
, but the clip isn't embeddable, so you'll need to actually go to the site to view it.
Mary Connors - 1974
The 1974 attempt
San Rafael Daily Independent Journal - Aug 28, 1974
Asbury Park Press - June 6, 1975
The Bryan Eagle - Jan 25, 1976