Guess what it is?

The four prongs on the end looked like a sunshade with the cover taken off for winter, but no!

I had to ask a local in the end, apparently it's a fishing hut. I still imagined it incorrectly, until I got home and googled a photo of what it looks like when set up:
https://www.dreamstime.com/rhine-river-old-fishing-hut-basel-switzerland-old-city-center-basel-munster-cathedral-background-image163477689

[Christine Sztukowski]

Very interesting information, Lovely scene

[Lesley]

Fascinating!

[Annie-Sue]

It's like people fishing in Morecambe Bay - I'd be very iffy about eating anything puled out of there ;-)

[Issi Bannerman]

Well then, we've learned something new today! Nice image and info.