Triangle Marsh is a wetland of the San Francisco Bay, situated at the base of Ring Mountain at the north end of the Tiburon Peninsula in Marin County, California.

Archaeological Pecked curvilinear nucleated petroglyphs, and recovery on Ring Mountain, hold significant evidence of Native American habitation and likely proof that early Miwok peoples exploited marine resources from Triangle Marsh.

The 31-acre (130,000 m) property is owned by the Marin branch of the National Audubon Society who restored upland and wetland habitats there with funding from a variety of sources. Federal endangered species, including the clapper rail and salt marsh harvest mouse, live in the Marsh.

• Strawberry Spit
• Class of 1918 Marsh

• Chuck Morton and Michael Galloway (2006) Tidal marsh restoration at Triangle marsh, Marin County, John Muir Research Institute
• C. Michael Hogan (2008) Ring Mountain, The Megalithic Portal, ed. A. Burnham
• Marin Audubon Society Restoration Page

37°55′20″N 122°29′48″W / 37.922294°N 122.496657°W / 37.922294; -122.496657