The first man, believed to be in his 50s, was found in Rivière-des-Prairies, between Montreal and Laval. The discovery was made near 15th Avenue and Gouin Boulevard.
Later around 3 p.m. on the St. Lawrence River, people on a boat found the second man, 59, near the Mercier bridge.
A police spokesperson says the two cases do not appear linked, despite the coincidence of finding them on the same day.
The bodies did not appear to shows signs of violence. However, authorities will carry out autopsies to determine the causes of death.