Know Before You Go
This site is tucked away inside of the Słowinski National Forest and rarely advertised. Following the main trail to the sand dunes, the entrance is halfway to the other end of the park, about 2.5km (a mile and a half).
From the entrance of the park, where you can leave your car, there is a main trail. Walking takes between 30-45 minutes and is a beautiful trail through the marsh. You can pay for an electric golf cart to ferry down the path, or you can arrive by actual ferry. By far the easiest thing is to rent a bike at the entrance, or from any of the vendors in the area, and take the ride yourself. A small fee gets you in, about 7.50 złoty (about $2 US), cash only.
Once there, in addition to the V2 rocket shell there is a wide variety other rockets and missiles on display which were catapulted into the heavens from this location, German and Soviet alike.