Museumhaven Zeeland keeps a small fleet of historic vessels in and around the old harbour. It is a modest place, but it suits Zierikzee: boats, quays, shipyard work, and maritime history are easier to understand here than behind glass.
The outdoor harbour collection is the main draw, with old working boats that give the waterfront some life even when nothing much is happening. Check opening times if you want the yard or indoor parts; otherwise treat it as part of a harbour walk.