The U.S. National Oceanic and Atmospheric Administration (NOAA) and the U.S. Navy are engaged in a multi-year effort to monitor underwater sound within the U.S. National Marine Sanctuary System. The agencies are working with numerous scientific partners to study sound within seven national marine sanctuaries and one marine national monument, which includes waters off the east coast region of the United States (Stellwagen Bank, Gray’s Reef and Florida Keys National Marine Sanctuaries), the west coast region (Olympic Coast, Monterey Bay and Channel Islands National Marine Sanctuaries) and the Pacific region (Hawaiian Islands Humpback Whale National Marine Sanctuary and Papahānaumokuākea Marine National Monument). The project is designed to provide standardized baseline information important for contextualizing both how much sound is introduced within these protected areas by specific sources and potential impacts to the areas’ marine taxa and habitats. For more information, see https://sanctuaries.noaa.gov/science/monitoring/sound/.