St. Catharines is a city located in Southern Ontario, Canada. It serves as the most populous city within the Niagara Region and ranks as the eighth-largest urban area in the province. The city covers an area of 96.2 square kilometres (37.1 mi2) and had a population of 136,803 as of 2021.
Geographically, St. Catharines is situated 51 kilometres (32 mi) south of Toronto across Lake Ontario and lies 19 kilometres (12 mi) inland from the international boundary with the United States along the Niagara River. It serves as the northern entrance to the Welland Canal.
The city is officially known by the nickname "The Garden City," a title attributed to its extensive green spaces, which include 4 square kilometres (1.5 mi2) of parks, gardens, and trails.