The Russian Navy hovercraft is currently the largest in the world and takes a while to come to a stop. So what happens when you have a Navy exercise on an afternoon when the local populace has decided to spent the afternoon on the beach…which just happens to be part of a Navy training area? Oops.
The beach is not a public area but obviously it wasn’t closed off very well to the public either. Thankfully nobody was hurt.
Kaliningrad is not connected to Russia geographically so in that sense is similar to how Hawaii or Alaska are separated from the mainland USA. It belonged to a country named Prussia (German) that no longer exists and after WWII was given to Russia by the Western Powers. It is Russia’s only ice free link to the Baltic Sea.