The Bay of Quinte is on the northern shore of Lake Ontario.

Located about 200 kilometers from Toronto and 400 from Montreal, the Bay of Quinte is a long, thin bay in the shape of a letter "Z". The northern side of the bay is defined by the mainland, while the southern side follows the shore of the Prince Edward County headland. Beginning in the east with the outlet to Lake Ontario, the bay runs west-southwest for 25 kilometers to Picton, where it turns north-northwest for another 20 kilometers as far as Deseronto . From there it turns south-southwest again for another 40 kilometers, running past Big Island on the south and Belleville on the north. The width of the bay rarely exceeds two kilometers. The bay ends at Quinte West (formerly Trenton) and the Trent River, both also on the north side. The Murray Canal has been cut through the few miles separating the end of the bay and Lake Ontario on the west side. The Trent River is part of the Trent-Severn Waterway, a canal connecting Lake Ontario to Lake Simcoe and then Georgian Bay on Lake Huron.