The Nore is a sandbank at the mouth of the Thames Estuary, England. It marks the point where the River Thames meets the North Sea In previous years, it marked the Port of London Authority's seaward limit.
Since the sandbank could be a hindrance to passing ships, in 1732 it got the world's first lightship. This became a major landmark, and was an assembly point for shipping. By 1919 there were nine lightships. Now the job is done by a buoy.