Kankakee River State Park is an Illinois state park on 4,000 acres (1,619 ha) primarily in Kankakee and Will Counties, Illinois, United States. Originally, 35 acres (14 ha) of land was donated by Ethel Sturges Dummer for the creation of the state park in 1938. Another 1,715 acres (694 ha) was donated by Commonwealth Edison in 1956, which again donated more land in 1989. The islands of Smith, Hoffman, Langham, and Willow are all located inside the park on the Kankakee River.
The Kankakee Torrent was a catastrophic flood that occurred about 19,000 calibrated years ago in the Midwestern United States. It resulted from a breach of moraines forming a large glacial lake fed by the melting of the Late Wisconsin Laurentide Ice Sheet. The point of origin of the flood was Lake Chicago. The landscape south of Chicago still shows the effects of the torrent, particularly at Kankakee River State Park and on the Illinois River at Starved Rock State Park.