San Diego Bay is the reason San Diego, California is such an important port city, both for the Navy, commercial shippers and cruise ships. It's considered one of the best natural harbors on the west coast, and spans 34 miles of waterfront. The bay includes several marines, a cruise ship terminal, Navy and commercial shipyards and the Sweetwater Marsh National Wildlife Refuge. It also is home to upwards of 75 Navy vessels and two on-the-water museums: the U.S.S. Midway and the San Diego Maritime Museum. San Diego Bay also is popular for fishing, either from shore or by boat, with plenty of sand bass, spotted bay bass, halibut and bonefish.