About the Reef
Duxbury Reef is a beautiful and fascinating place to visit!
It is one of the largest shale reefs in North America, and includes a stretch of sandy beach. During low tide, the shale reef’s fractures and channels form extensive tidepools filled with a variety of macro algae species, small fish like monkeyface pricklebacks, crabs, turban snails, and other amazing tidepool dwellers. California mussels and gooseneck barnacles cling to rock surfaces, sifting bits of food from the water that washes over them with the returning tide. The conservation area’s sandy seafloor and surfgrass beds support perch, flatfish, nudibranchs, crab, and other species. In fact, researchers and community scientists have identified over 200 different species of invertebrates, seaweeds, and marine plants that cling to the reef as the tide ebbs and flows, as well as small fish and seabirds that frequent the reef.
Visiting Duxbury Reef
The gentle slope of the extensive reef makes exploring the tidepools on foot accessible to almost everyone and has become a popular destination for people seeking to explore this type of habitat. However, increasing visitation is taking its toll on the intertidal life of the reef, and many visitors are unaware of its ecological sensitivity and protected status.
Duxbury Reef is designated by the state of California as a State Marine Conservation Area (a type of marine protected area, MPA). It lies adjacent to, and contiguous with Marin County’s Agate Beach Park, and Point Reyes National Seashore, and is part of the Greater Farallones National Marine Sanctuary. It is also designated by California as an Area of Special Biological Significance. Many of California’s unique coastal places are safeguarded by a network of 124 marine protected areas (MPAs), managed by the California Department of Fish and Wildlife.
At Duxbury Reef State Marine Conservation Area, all marine life and physical resources are protected:
It is unlawful to injure, damage, take, or possess any living, geological, or cultural marine resource for recreational and/or commercial purposes, with the following specified exceptions:
The recreational take of finfish* from shore and abalone is allowed, but must comply with California Department of Fish and Wildlife regulations.
*Currently, the recreational abalone fishery is closed until April of 2026.
In summary, visitors should know that the collection of rocks, shells, algae or seaweed, and any marine life (except for finfish from shore by hook and line) is prohibited at Duxbury Reef. Marine protected area restrictions are in place to protect and restore ocean habitats and increase the health, productivity, and resilience of ocean ecosystems.
Learn More: SF Chronicle Article:
Reef visitors urged to use ‘light footprint’
Group Visits
Visiting groups may request an informal docent reef tour, which includes an introduction to Duxbury Reef habitat and rocky intertidal ecology, the reef’s protected status as an MPA, and protective tidepooling practices. Docents will also be available on the reef to answer questions about the marine life that group participants discover as they explore.
A Marin County Parks visiting permit is required for groups of 20 or more visitors.
Get a Group Permit with Marin County Parks and Open Space.
If your group of 10 or more people would like to request a docent tour, click below and fill out our form.
Look Up Tides
Protective Tidepooling PRactices
Duxbury Reef is an exciting place to explore. To observe rocky intertidal marine life at low tide, check the tides while planning your visit. Please also help protect the health of the reef and marine life by adhering to the following guidelines:
1. Observe with your eyes, not with your hands. Many creatures found on the reef can be injured if picked up by even the most well-meaning person. Limited, gentle, two-finger touching of immobile, firmly attached marine life is ok, e.g. mussels, limpets, chitons, barnacles, sponge, tunicates, sea stars and urchins (only if firmly attached to the reef) and plants or algae. Do not touch or disturb mobile, unattached, or lightly attached marine life such as fish, eels, crabs, nudibranchs, hermit crabs, snails or octopus. This includes never feeding reef animals.
2. Leave everything in its place. Never pick up or move any rocks, animals and algae, including shells. Many creatures are specifically adapted to the conditions in the tidepool where they are found (including presence or absence of other species, temperature, degree of exposure to wave force, extent of exposure to light, size of space beneath larger rocks, etc.).
3. Take care where walking. Walk gently on exposed rock and try to avoid stepping in pools of water, on plants, algae, or animals. Creatures and algae on the reef can be crushed by footsteps. Try to step on the bare rock, try not to scuff feet. Do not walk through the tide pools, even small shallow pools, as small invertebrates are sheltering, may only be feeding when the tide is out, and egg masses are present in shallow pools or on exposed rock but are easily destroyed. Remember there are many invertebrates (including juveniles) sheltering in the fields of exposed algae, hidden beneath the algae, and they are crushed as visitors walk through the algae.
4. Stay away from the bottom of cliffs. No climbing on or digging at fragile cliffs. The cliffs are unstable and can crumble or collapse suddenly and unexpectedly and can result in severe injury or death. Also, increasing the natural rate of bluff erosion increases the sediment load in the tide pools and can be harmful.
5. Run and play on the sandy beach, not on the reef. Visitors may slip and harm themselves and wildlife if these activities take place on the reef.
6. Take your time. The longer you look, the more life you will notice that you did not initially see.
7. Dogs must be leashed and should not be taken into the intertidal zone.
8. Maintain 100-foot distance (6 car lengths) from any marine mammal. Seals and sea lions are sometimes observed along the Reef. Avoid making the animals aware of your presence. Remember that pups may be left alone on the beach while the mother feeds. Do not touch or take photographs with the animals.
9. Always watch the ocean and stay aware of the rising tide.
