Ontario is Canada's most populous province and, in many ways, its centre of gravity. It borders four of the five Great Lakes and Hudson Bay to the north, stretching from the densely urban south to boreal forest and genuine wilderness that most Canadians have never seen. Two of the country's most visited cities — Toronto and Ottawa — sit here, along with Niagara Falls, the Thousand Islands, and some of the best canoeing lakes on the continent.
Toronto is the obvious starting point: a genuinely cosmopolitan city with excellent restaurants, a strong arts scene, and the kind of energy you'd expect from a place where over 200 languages are spoken. Ottawa is a different animal — quieter, more walkable, with world-class museums and the spectacle of Parliament Hill. Both are worth several days.
Beyond the cities, Ontario rewards patience. The Bruce Peninsula offers dramatic limestone cliffs and turquoise water that looks borrowed from the Caribbean. Algonquin Provincial Park is a classic canoe-tripping destination. Point Pelee, at the southern tip of the province, is one of North America's great birding sites. Up north, Pukaskwa on Lake Superior is for people who want the real wilderness experience with no shortcuts.
The province spans so much latitude that weather varies significantly — Toronto gets proper hot summers and cold winters, while the north stays cool well into June. July and August are peak season almost everywhere. If you're heading into the parks for paddling or hiking, May and September offer fewer bugs and smaller crowds.