What geographical feature is Toronto notably positioned near?

Toronto is notably positioned near Lake Ontario, which is one of the five Great Lakes of North America. This proximity to Lake Ontario has significant implications for the city's climate, economy, and recreation. The lake acts as a moderating influence on the weather, making winters milder compared to other regions at similar latitudes, and helps to maintain a vibrant ecosystem and recreational opportunities such as boating and fishing. Additionally, the waterfront area of Toronto, with its parks, trails, and attractions, draws both residents and tourists, enhancing the city's appeal and livability.

While the other geographical features mentioned, like the Rocky Mountains and Niagara Falls, are well-known, they are not directly adjacent to Toronto. The St. Lawrence River flows further east and is significant for trade and the shipping industry, but it does not define Toronto's immediate geographical identity as strongly as Lake Ontario does. Thus, the correct answer reflects Toronto's direct relationship and dependence on Lake Ontario for various aspects of life in the city.