Ambient noise in the ocean is a topic that has been widely studied since the 1940s. Over the last 25 years the effects of noise on marine organisms has become a concern. The primary issue has been the potential of noise to adversely affect marine mammals. The Stellwagen Bank National Marine Sanctuary (SBNMS) and upper estuary of the St. Lawrence River are sites where the degradation of habitat due to increasing noise levels is a concern because they are feeding grounds and summer havens for numerous species of marine mammals. In an effort to provide information for better sanctuary management this report describes the current understanding of ambient noise and existing levels of ambient noise and its relationship to marine mammals in the Stellwagen Bank National Marine Sanctuary and the designated marine park area of the Upper St. Lawrence River Estuary.