Greenwell State Park is a public recreation area located on the Patuxent River in St. Mary's County, Maryland.

[2] The state park features the historic Rosedale Manor House[3] as well as the Bonds-Simms tobacco barns complex.

Park activities include hiking, cycling, horseback riding, fishing, picnicking, hunting, swimming, and canoeing.

[2] The park originated in 1971, when John Phillip Greenwell, Jr. and his sister, Mary Wallace Greenwell, donated their 167-acre (68 ha) farm to the state for use as a public park.

The state subsequently purchased the adjacent 430-acre (170 ha) Bond property and added it to the park.