Otsego Lake is a 4,046-acre (16.37 km2) lake located in Otsego County in the U.S. state of New York. It is the source of the Susquehanna River and largest lake in Otsego County. The Village of Cooperstown is located at the lake's southern end. Glimmerglass State Park is located on the lake's northeastern shore, and includes Hyde Hall, a large mansion constructed in 1817, that overlooks the lake. The Glimmerglass Opera, opened in June 1987, is located on the western shore.

Otsego County is a county in the U.S. state of New York located within the Mohawk Valley Region. As of the 2020 census, the population was 58,524. The county seat is Cooperstown. The county's population center is Oneonta. The name Otsego is from a Mohawk or Oneida word meaning "place of the rock." The county is part of the Mohawk Valley region of the state.