For non-sea sights, and if you are willing to drive just a bit, a walk/hike in the
Lüneburg Heath is great and different. The town of
Lüneburg is also very pretty. A little farther afield is the
German Tank Museum in the town of Munster, which I found very interesting. And of course the
Bergen-Belsen Memorial, where Anne Frank perished, is in that vicinity too.