Hart-Miller Island State Park is a 244-acre public recreation area at the mouth of Back River in Essex, Maryland, accessible only by boat. It includes part of a larger Chesapeake Bay island complex, including Hawk Cove and Pleasure Island, and centers on Hart-Miller Island, formed by joining the natural islands of Hart and Miller. After the state acquired the islands in the late 1970s, a dike built in 1983 enclosed land later filled with dredged material from Baltimore Harbor and the Patapsco River, creating about 1,100 acres. The park is notable as a recreation landscape shaped by major harbor engineering, with a sandy beach, trails, camping, and boating access.