With water temperatures of only 6 degrees, it doesn't take long before your arms and legs lose feeling.
A man was taken to hospital, after being pulled from Lake Ontario, near Sugar Beach in Toronto.
He was later pronounced dead in hospital.
The call came into Toronto Police at around 11:15 on Monday morning from passer-bys, who noticed a commotion in the lake.
A woman jumped in after him and tried to pull him to safety, but failed.
The Police Marine Unit was on scene quickly and managed to help the woman out of the water, but lost sight of the man.
He was found by police divers a short time later, and taken to hospital without vital signs.
Police will only say he's a man in his 30's but aren't sure if he was swimming or if he fell into the water.
However, they do say alcohol may have been a factor.