Ocean Roar is a small cluster of buildings located at the mouth of Walker Creek on Tomales Bay, about 2.3 miles (3.7 km) southwest of Tomales and 16 miles (26 km) west of Petaluma, California. It was formerly a community on the North Pacific Coast Railroad. Walker Creek originates at the confluence of Salmon Creek and Arroyo Sausal, flowing west to join Keyes Creek before emptying into Tomales Bay. Walker Creek is named after Lewis W. Walker, an early landowner in the region. Keyes Creek, also known as Keys Creek, is named for John Keyes, who settled there in 1849. This creek was once an important waterway used by Keyes to transport agricultural produce to San Francisco.

In 1874, the North Pacific Coast Railroad began operating north from Sausalito, skirting the eastern shore of Tomales Bay. It passed through small communities such as Ocean Roar and Tomales before entering the redwood country at the Russian River. During its 60-year existence, the railroad transported millions of board feet of prime redwood lumber to San Francisco, as well as farm and dairy products. It also provided a vital link for the urban population to escape the city for weekend retreats. However, the route was abandoned in 1930 as highways made driving more convenient. The site of Ocean Roar is now marked by a highway callbox.

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. In the 1970s, the Soulajule Reservoir was built on Arroyo Sausal following a severe drought; the resulting lake inundated the Franciscan and Cycle mines. The largest mine, located at the Gambonini Ranch near the confluence of Salmon Creek and the mainstem Walker Creek, closed in 1970. In 2003, the California Department of Fish and Wildlife began efforts to reestablish coho salmon in Walker Creek. Read more here and here. Explore more of Ocean Roar and Walker Creek here: