The U.S. Lightship Service was started in 1820. Like lighthouses and buoys, lightships were navigational aids. The lights atop their masts were similar to those in lighthouses, but their portability made them much more versatile.

The Lightship PORTSMOUTH was built in 1915. She served for 48 years off the coasts of Virginia, Delaware and Massachusetts helping mariners avoid dangerous shoals or enter safely into harbors at night. Typically, the ship would anchor at a strategic location at sea and remain there for months at a time. The maximum crew for the Lightship PORTSMOUTH during her half-century in service was 15 men.

In 1964, she was retired to Portsmouth and renamed according to the custom of naming lightships after the site where they are stationed. In 1989, the Lightship PORTSMOUTH was designated a National Historic Landmark. Now a museum, the ship’s quarters are fitted out realistically and filled with fascinating artifacts, uniforms, photographs, models, and more.