Ocean Roar is a small group of buildings at the mouth of Walker Creek on Tomales Bay, and formerly a community on the North Pacific Coast Railroad, about 2.3 miles (3.7 km) southwest of Tomales and 16 miles (26 km) west of Petaluma, California. Walker Creek originates at the confluence of Salmon Creek and Arroyo Sausal and flows west joining Keyes Creek and then flows into Tomales Bay. Walker Creek is named for Lewis W. Walker, an early landowner in the area. Keyes Creek, or Keys Creek, is named for John Keyes, who settled on the creek in 1849 and used this once-important waterway to transport agricultural produce to San Francisco.

In 1874, the North Pacific Coast Railroad ran north from Sausalito, skirting the eastern shore of Tomales Bay, passing through small communities such as Ocean Roar and Tomales before entering the redwood country at the Russian River. In its 60 year life, the railroad hauled millions of board feet of prime redwood lumber to San Francisco along with farm and dairy products. The rail also provided a lifeline for the growing urban population to escape the city for a weekend, but the route was abandoned in 1930 when the highway made driving more convenient. The site of Ocean Roar is now marked by a highway call box.

Mercury was mined at several sites in the Walker Creek watershed through the 1960s and early 1970s including the Gambonini, Chileno Valley, Franciscan, and Cycle mines. Soulajule Reservoir was built in the 1970s on Arroyo Sausal following a severe drought and the resulting lake inundated the Franciscan and Cycle mines. The largest mine, at the Gambonini Ranch near the confluence of Salmon Creek and mainstem Walker Creek, closed in 1970. In 2003, the California Department of Fish and Wildlife began an effort to reestablish coho salmon in Walker Creek. Read more here and here. Explore more of Walker Creek here: