Gananoque is a town in the Leeds and Grenville area of Ontario, Canada. The town had a population of 5,383 year-round residents in the 2021 Canadian Census, as well as summer residents sometimes referred to as "Islanders" because of the Thousand Islands in the Saint Lawrence River, Gananoque's most important tourist attraction. The Gananoque River flows through the town and the St. Lawrence River serves as the southern boundary of the town.