Sometime approximately 214 million years ago, an asteroid about 3 miles wide made a big impression on the Canadian province of Quebec.
Shock waves generated by the massive collision left behind a pattern of concentric rings. The outer rings, with a total diameter of around 64 miles, were heavily eroded by glaciers over time and are difficult to discern. The tougher composition of the inner rings proved more resistant to erosive forces, and it is these inner rings, with a diameter of about 37 miles, which form the banks of Lake Manicouagan. Although the impact did occur toward the end of the Triassic period it is NOT believed to have precipitated a significant global extinction.
A dam was constructed across the Manicouagan River in the 1960s, raising the water level and creating the fully annular (ring-shaped) body of water we see today, which serves as a large reservoir.
Manicouagan is the largest crater visible from space, and the sixth-largest verified impact crater in the world.
Middle School link: https://er.jsc.nasa.gov/seh/Exploring_Meteorite_Mysteries.pdf#page=60
High school link: https://mass.pbslearningmedia.org/resource/incoming/incoming/