USS Nereus was a 1244-ton screw steamship purchased by the Navy October 1863, while she was under construction at New York City. Commissioned in April 1864 and assigned to the North Atlantic Blockading Squadron, she operated off Wilmington, North Carolina, until August. In September 1864 she escorted a commercial steamship to Panama, then underwent repairs at the New York Navy Yard. Later in the year Nereus assisted monitors on their voyages to southern waters and, in December, took part in the initial, abortive attempt to capture Fort Fisher, North Carolina, which protected the main water route to Wilmington.

After the Fort Fisher was finally captured in mid-January, thus closing Wilmington to the blockade running trade, Nereus towed a monitor to Charleston, South Carolina. Soon afterwards she went to the Bahamas and the Caribbean to guard against the threat represented by the Confederate raider Shenandoah, whose actual presence in the Pacific area was then unknown to Federal authorities. Nereus returned to New York in early May and was decommissioned. Sold in mid-July 1865, she entered commercial service under the name Somerset. She was broken up in 1887.