Harderwijk is an old Hanseatic town on the Veluwemeer, the lake that replaced this stretch of the former Zuiderzee. It has a compact medieval centre, a marina where fishing boats once worked, and enough old gates and church towers to make a wander worthwhile.
The town's best-known attraction is the Dolfinarium, the large marine mammal park near the waterfront. Even if you skip it, Harderwijk still has a clear identity: a fortified trading town that turned from sea fishing to lakefront leisure after the Dutch reshaped the water around it.
It works best as a low-pressure day trip from the Veluwe, Zwolle, or Amersfoort. Walk through the old streets, visit the Stadsmuseum, pass the Vischpoort, and finish by the harbour where the old coast now feels partly inland.