Holbrook Island Sanctuary State Park is a public nature preserve on Penobscot Bay in Brooksville, Maine, spanning 1,345 acres of mainland shore and offshore island. Its terrain includes upland forest, meadows, marshes, ponds, and rocky coast, offering a broad range of coastal habitats. The park was established in 1971 after Anita Harris donated 1,230 acres she had assembled in Brooksville since the 1960s. In accordance with her wishes, it has remained largely in its original state with minimal modern development. Older trails and the bay support hiking, cross-country skiing, swimming, kayaking, and fishing.