Zhoushan Museum gives useful context for a city-region that many travellers experience only through ferries, seafood, and the route to Putuo Mountain. Its exhibits cover the archipelago's maritime setting, fishing culture, settlement history, and the role of the islands in regional trade and religion.
The museum is a good first stop if you are spending time in Zhoushan rather than just passing through. Understanding the islands as a working maritime landscape makes later visits to Shenjiamen, Zhujiajian, and Putuo feel less like disconnected stops and more like parts of one sea-facing city.