Frenchman's Bay lies on the north shore of Lake Ontario about 20 miles North East of Toronto or approximately Latitude 43° 48.53' North and Longitude 79° 04.59' West.

It is a well-sheltered bay protected from the force of storms by a narrow sand bar named Fairport Beach. The Pickering Harbour Company Limited constructed the channel entrance leading into Frenchman's Bay in the 1840's. The entrance to Frenchman's Bay is 50 feet wide and is protected by two parallel breakwaters about 100 feet apart and extend about 400 feet into Lake Ontario. There are five red and five green spar buoys leading into the bay. Boaters entering the harbour should stay centred between these buoys.

The usual navigation season is from mid April to the end of October. Ice generally begins to form in places on the bay in early December.

The Toronto Weatheradio Canada Station broadcasts marine weather reports continuously on 162.475 MHz (VHF Channel W3).