Tourism contributes heavily to the economy of Central Ontario, peaking during the summer months owing to the abundance of fresh water recreation and wilderness found there in reasonable proximity to the major urban centres. At other times of the year, hunting, skiing and snowmobiling are popular. This region has some of the most vibrant fall colour displays anywhere on the continent, and tours directed at overseas visitors are organized to see them. Tourism also plays a key role in border cities with large casinos, among them Windsor, Cornwall, Sarnia and Niagara Falls, the latter of which attracts millions of US and other international visitors.