SS Peralta is a concrete floating breakwater in the Powell River in British Columbia. She was built as a concrete oil tanker by the San Francisco Shipbuilding Company, and was launched in February 1921. Her sister ship is SS Palo Alto. She was acquired in 1924 and converted into a sardine cannery in Alaska. After spending 24 years in this role the ship was moored off Antioch, California. She was bought by Pacifica Papers in 1958 and moored as part of a giant floating breakwater on the Powell River to protect the company's log storage pond. She is the oldest and largest American-built concrete ship still afloat.