Bremerhaven Lighthouse, also called the Simon Loschen Tower, is a handsome brick harbour light near the New Harbour. It is not a major museum stop, but it gives the waterfront a useful historical marker among newer visitor buildings.
Look for it while walking between the Havenwelten sights. Its value is visual and contextual: a reminder that Bremerhaven's tourist waterfront is still layered over a working maritime city.