The NRP is looking for witnesses, after car hit a tree and entered the Welland Canal in St. Catharines.
Police were called out to the Glendale Ave and Welland Canals Parkway area, shortly after 2:00 a.m. this morning.
That portion of the canal had been drained weeks ago, so the car came to a stop in about 3 feet of water.
Officers say there were six people inside the car at the time.
A man in his 20's had to be taken to an out of town trauma centre with serious injuries.
The other passengers were treated for non-life threatening injuries in hospital.
The NRP says the suspected driver ran away on foot.
The vehicle sustained about $20,000 in damage.
Police say it was a blue Audi A4 Avant, with four doors in the 2009 model year.
Anyone with information regarding this incident should contact Niagara Regional Police by calling 905-688-4111 with extension 4233.
The investigation is ongoing.