Three dancing dolphins

Deep in the woods of Brandenburg, Germany, in a devastated area of a former military base used by the Red Army of the Soviet Union, a soldier has left this beautiful picture of three dancing dolphins.

It's not the regular kind of street art. If you're lucky enough to find the place, you will that it isn't a painting. No, it's a mosaic, made of hundreds of small and handmade stones.

But why dolphins? Behind the floor with the picture waits the abandoned indoor pool where submarine fighters held their trainings...