Diver exploring a shipwreck
The F/V Patriot offers opportunities for exploration. Photo: Matthew Lawrence/NOAA

The sanctuary offers scuba divers a chance to explore an exciting offshore environment at the mouth of Massachusetts Bay. Exposed waters create challenging dive conditions but offer rewarding experiences. Although most of the sanctuary is deeper than the recommended recreational scuba diving depth limits, some 15%, or 126 square miles, is shallower than 130 feet at low tide. Much of that area lies atop Stellwagen Bank, with the rest on southern Jeffreys Ledge and the top of Sanctuary Hill.

What Animals Will I See?

Different dive sites support different communities of life; plan your dive.

Dive Sites

Dive in and explore natural habitats or shipwrecks -- the sanctuary has both.

Diving Conditions

In addition to deep, cold water that rarely rises above 50 degrees Fahrenheit, you will likely experience strong currents at the surface and the bottom, especially if the wind and tide are moving in the same direction. Plan your dive around slack tide for the best underwater and surface conditions. Watch for hazards, especially fishing gear. Gill nets in the water column pose the greatest entanglement threat to divers because they are hard to see and are hard to remove. Additionally, monofilament lines, lobster pot lines and trawl nets can also ensnare divers. Be particularly aware of your surroundings. Fishermen and boaters in the area may not be aware of divers in the water.

Mooring Buoys

The sanctuary works with the dive community to install mooring buoys at dive sites in an effort to protect the sites from inadvertent damage from anchoring. Boat operators should work with their dive team leaders to tie onto these subsurface moorings located in proximity to sensitive dive sites.

Divers holding on to a mooring buoy
Divers install a mooring buoy at a sanctuary shipwreck dive site. Photo: Matthew Lawrence/NOAA
Diving Tips
Diving flags
The Diver Down flag is flown when divers are in the water and the Alpha flag is flown when a vessel’s mobility is restricted. The Alpha flag may be flown along with the Diver Down flag when divers are in the water. Photo: Dive World
  • Use the tide station at Boston Light or Race Point to provide an estimation of slack tide (slack tide on Stellwagen Bank usually occurs 30 minutes before high or low tide at the tide station).
  • Slack tide for Jeffreys Ledge and Sanctuary Hill is best indicated by the tide station at Rockport, Mass.
  • Fly both the Diver Down flag and the Alpha flag to indicate to other vessels that divers are in the water, as sanctuary waters can be quite busy
  • Since the water temperatures are always cold, thick wetsuits or drysuits (if certified) make diving safer and more comfortable.
The activities described here are inherently hazardous and should only be engaged in by physically fit and experienced divers. All risks of injury are assumed by individual participants, who are responsible for taking appropriate safety precautions, and using appropriate equipment when diving.
A diver holding a camera in the water
A drysuit is recommended as are strobe lights on arms to lessen backscatter from particles in the murky water. Photo: Deborah Marx/NOAA


Although diving is allowed throughout the sanctuary, regulations are in place to protect historic resources and marine mammals. Under 15 CFR 922.142, divers are not permitted to grapple a shipwreck, drop a down line directly onto a shipwreck, or tie a down line onto any part of a shipwreck. Divers are also not allowed to leave an unattended mooring in the sanctuary at any time or remove any object from a historic resource.

Diving when in the vicinity of whales is considered harassment and is punishable under federal law. Any boating activity that harms or causes a whale to change its behavior is also a violation of the Marine Mammal Protection Act and the Endangered Species Act, if applicable.

For a detailed listing of sanctuary regulations, visit our Manage Section.