Apparently an action cam was forgotten by a young boy, got caught by the North Sea and drifted from the east coast of England to one of our islands at the west coast north of Hamburg. There it was found - still functioning! - and the German SAR service DGzRS performed a drift analysis.
Unfortunately the story is in German only, with a video at the bottom of the page:
Maybe you guys may help to identify the youngster.
By the way, DGzRS have some nice footage: