Waterloo Regional Police have confirmed a female body has been found in the Grand River in Kitchener near Riverbend Drive.
Police believe the age of the female is somewhere between 20 and 50.
Investigators have released a photo of a tattoo found on the woman's torso which was pink with stars.
"[The tattoo] is very distinctive. We're hoping the public is going to be able to assist us in identifying the victim," said Inspector Mark Bullock.
Bullock added the woman also had a navel piercing.
Investigators say at around 4:00 pm, teenagers swimming in the river spotted the body floating in the water and called police.
The homicide team, forensic unit and the coroner's office was at the scene on Friday night.
"There's a significant number of resources being poured into this," said Bullock.
Police believe the circumstances are suspicious and suspect foul play is involved.
A post-mortem is expected in Hamilton on Saturday.
Police are asking anyone with information related to this incident to call the homicide branch at 519-650-8500 ext. 8642 or Crime Stoppers at 1-800-222-8477.