The mid-section of the New Bedford-Fairhaven bridge, seen in the middle of this picture, rotates to open and close. We saw that happen twice during our time in the harbor.
Here’s what DJ found on Wikipedia about how the lightship came to be in Nantucket.
WLV-613 (which was originally the Ambrose lightship) was berthed at the Wareham Shipyard along Main Street in Wareham, Massachusetts from about 1990 until she was moved to New Bedford, Massachusetts on December 1, 2014. The vessel (now painted as “NANTUCKET”) is now privately owned by William B. Golden and Kristen Golden, owners of WLV-612 that also served as the Nantucket station lightship. Currently, she is located in New Bedford, MA but closed to the public.