USS Plunger (SS-2) was one of the earliest submarines of the United States Navy. She was the lead boat of her class and was later renamed A-1 when she was designated an A-type submarine. She is not to be confused with the experimental submarine Plunger which was evaluated by the U.S. Navy from 1898 to 1900, but not accepted or commissioned.

USS Plunger was an experimental submarine built for the United States Navy. She was ordered in 1895 and launched in 1897, but was never commissioned for active service. She is not to be confused with the later USS Plunger (SS-2), a.k.a. A-1, which served in the Navy from 1903 to 1913.