The Plumbush Marshes are a wetland area located in Newbury. The marshes are an important site for environmental education and research, as they provide a natural habitat for studying the effects of climate change, pollution, and invasive species on wetland ecosystems. The Plumbush Marshes are open to the public for hiking, birdwatching, fishing, and canoeing, but visitors are advised to respect the fragile nature of the marshes and follow the rules and regulations of the area.

Plumbush Marshes are west of Plum Island on the south side of the Plum Island Turnpike.