Den Helder's maritime past is its main draw. The Marinemuseum at the historic Willemsoord dockyard is the standout attraction — it traces four centuries of Dutch naval history with ship models, navigational instruments, and full-sized vessels you can board, including the ironclad HNLMS Schorpioen and the celebrated minesweeper HNLMS Abraham Crijnssen. The Reddingsmuseum Dorus Rijkers is a smaller but worthwhile museum on sea rescue.
The fortifications around the city are equally impressive. Fort Kijkduin and Fort Harssens are part of the broader defence lines protecting the naval base. The Lange Jaap lighthouse, the tallest in the Netherlands, rises from the dunes near Huisduinen. Walking or cycling the coastal dike from the city to Huisduinen Beach and back takes in all of these in a half-day loop.