Crystal Lake State Park is a day-use state park and historic site in Barton, Vermont, United States. It is located at 96 Bellwater Avenue, off Willoughby Lake Road just east of the village, at the northwestern end of 763-acre (309 ha) Crystal Lake. It features a sandy beach with swimming area, and a bath house built by the Civilian Conservation Corps (CCC). A cottage is available for rental. The park was added to the U.S. National Register of Historic Places on August 30, 2005, for its association with the CCC.