Morro Bay is a natural embayment with an artificial harbor constructed by the U.S. Army Corps of Engineers. It is the only all-weather small craft commercial and recreational harbor between Santa Barbara and Monterey. Morro Rock was originally surrounded by water, but the Army built a large artificial breakwater and road across the north end of the harbor, linking Morro Rock and the mainland. Some of the rock used for this and for the artificial breakwaters was quarried from Morro Rock itself. Other rock was imported by barge from Catalina Island. The bay extends inland and parallels the shore for a distance of about 6.4 km (4 miles) south of its entrance at Morro Rock. Morro Bay is recognized for protection by the California Bays and Estuaries Policy.