Some surfers kicking back in the cold waters of the Eisbach river in downtown Munich, Germany.

The Eisbach is a small man-made tributary flowing down from the mountains and carrying a gusher of a torrent. It flows out from under a bridge at around 18 km/h and has for years created a standing wave that surfers can use.

The wave is created in a narrow area between two concrete walls, and there are some similarly unforgiving rocks just underneath the surface of the wave that have been known to collect kneecaps for souvenirs. They have been surfing this wave since the 70’s it seems, but back then the wave was a little less dependable.

More recently a few guys used some rocks, boards, a few strands of rope and a smattering of fluid dynamics theory to make the wave larger and more dependable.

See eisbach.de/ and en.wikipedia.org/wiki/River_surfing for more info.