lightship

Lightship is a term historically used to describe a ship that served as a lighthouse at sea. A lightship carried a powerful beacon, and often fog signals, to mark hazards and entrances where constructing a fixed lighthouse was impractical. The vessel was usually anchored at a designated position and crewed to maintain the light, operate signaling equipment, and monitor for navigation safety in its area.

Lightships were deployed by various maritime nations from the 19th through the mid-20th century, particularly in deep-water approaches, shoals, and busy harbor routes. As offshore lighthouses, automated lights, and buoy systems improved, the use of lightships declined. Many have been retired, some were preserved as museum ships, while others were sold or repurposed. They remain notable for their role in maritime safety and coastal history.

In contemporary usage, Lightship is the name of an augmented reality platform developed by Niantic. Introduced in the early 2020s, Lightship provides tools for building shared AR experiences on mobile devices, including real-world spatial mapping, anchoring digital content to locations, and enabling multiplayer interaction across devices. The platform is used by developers to create location-based games and practical AR applications.