The ol' bike-off-the-pier trick...
There was a kid on Chincoteague Island who tried that. Got his Darwin Award for it too.

(3 June 1999)

The setting is the Atlantic Ocean bordering Virginia. Chincoteague is a seaside town in Virginia, and Nathan and his family were vacationing there. One day he decided to copy the local boys, and ride his bicycle into the water. Apparently under the impression that his bike floated, he tied his wrist to the handlebar to make sure it wasn’t stolen by the surging waves. And then he rode along the Chincoteague Pier directly into the ocean. His bicycle didn’t float. Police and bystanders eventually recovered his body from 15 feet of water. He was airlifted to a Maryland hospital, where he was pronounced dead on arrival.
( The Resident Loon Not a demographic. Do not measure., Fri 2 Nov 2007, 18:31, Reply)