USS Castine (PG-6) was a gunboat of the United States Navy in commission from 1894 to 1901, from 1903 to 1905, and from 1908 to 1919. The first U.S. Navy ship named for Castine, Maine, she saw service during the Spanish–American War, the Philippine–American War, and World War I.

USS C-4 (SS-15) one of five C-class submarines built for the United States Navy in the first decade of the 20th century.