Hart-Miller Island State Park is a 244-acre (99 ha) public recreation area located at the mouth of Back River in Essex, Maryland.

The island comprising Hart and Miller with a total land surface of 1,100 acres (450 ha)—was acquired by the state in the late 1970s.

A dike was built joining Hart and Miller islands into Hart Miller Island in 1983, and the subsequent containment area was filled with dredge material from Baltimore harbor and the Patapsco River over the next 20 years.

[3][5] The park features a 3,000-foot (910 m) sandy beach, hiking trails, an observation tower, picnicking facilities, and sites for overnight camping.

The north cell of the island's 1,100-acre surface area is closed; the south cell officially opened for public access in May 2016.