Funny thing about Deer Island: it’s not actually an island. A hurricane in 1938 created the causeway that now connects the ‘island’ to the mainland. The other funny thing about Deer Island is that it is dominated by a gigantic sewage treatment plant, which is one of the keys to the cleanup of Boston Harbor. The facility is surrounded by 60 acres of parkland, with 5 miles of trails. Tours of the wastewater treatment facility are available with advance arrangements.
Deer Island is accessible only by car.