USS Mariner was a commercial tugboat operating in the Panama Canal area.

When World War I broke out, she was commissioned and armed by the United States Navy, and spent the rest of the war protecting vessels in the vicinity of the canal from German submarines.

The second ship to be so named by the U.S. Navy, Mariner, a 234 long tons (238 t) steam tug, was built at Camden, New Jersey, in 1906.

Following America’s entry into World War I, she was taken over by the Navy and commissioned 1 February 1918.

Mariner patrolled the approaches to the canal and provided tug and towing services during the remainder of World War I.