Because the area is so large, the temperatures in the region vary greatly. Generally, the summers are warm and the winters are cold and snowy. Southern Ontario gets a good amount of rain throughout the year, so rain gear is advisable when visiting the region. The southern region of Ontario along Lakes Ontario, Erie and lower Lake Huron is densely populated, while northern Lake Huron and Lake Superior are more forested with small lakes.
Water covers about one-sixth of the province's area.
These water routes are important to transportation. Hamilton, Port Colborne, Sarnia, Sault Ste. Marie and Toronto are important ports along the Great Lakes waterway. The North Channel and Georgian Bay in northern Lake Huron are popular cruising spots for boaters during the summer time. Manitoulin Island, separating the main water of Lake Huron from the North Channel is the world's largest fresh-water island.