Ontario, Erie, and Huron are all part of the Great Lakes, which are a group of five large freshwater lakes located on the border between the United States and Canada. Ontario is the most populous and second-largest of the Great Lakes, with a surface area of 19, 000 square miles. Erie is the fourth-largest lake, with a surface area of 9, 910 square miles. Huron is the second-largest lake, with a surface area of 23, 000 square miles. All three of these lakes are important parts of homes in both the United States and Canada, providing drinking water, recreational activities, and transportation routes.