Most names are essentially just landmarks of some sort.

Hamburg is derived from Hammer Burg, simply meaning hammer castle.

Part of Hamburg is Altona, which is lower German for all too near, because it’s really close to Hamburg.

East of Hamburg is Lübeck, which is means “settlement of the lub”, whoever the lub were.

Even farther east is Warnemünde, which is located at the mouth (Mund) of the river Warnow.

Said river is getting pretty wide a bit upstream, which gave the city of Rostock its name (“where the river gets wider”).

East of that: Stralsund. It’s the sound (the water kind) of Strela.

And so on and so on.

Tom Scott had some more info on that

https://youtu.be/NUyXiiIGDTo