hand paddlin'

A few weeks ago on an unseasonably warm Friday evening, we found ourselves walking along the Garonne. We had been walking a short while when we saw this-


It was a man, on some sort of flat boat, paddling upstream...with his hands and nothing else. He attracted a large audience along the shore, including a group of police officers, who eventually met up with him in a boat. I obviously have no idea what was exchanged between them, but the police boat left, and this guy kept paddling. And that's all I know.