Steller sea lion
Three Arch Rocks consists of 15 acres (6 ha) in three large and six small rocks located about a half mile (1 km) offshore from Oceanside. It is one of the smallest designated wilderness areas in the U.S., but features the largest colony of breeding tufted puffins and the largest common murre colony south of Alaska. It is the only northern Oregon pupping site for the threatened Steller sea lion.