Magnet fishers in Amsterdam use strong magnets to drag whatever sticks out of the murky waters of the canals. 
Discussion
Good haul!
He left quite a trail of scrap heaps along the route I ran
Oh that's a bit meh, do they bring it to metal collection for money? 🤔
I think they don't, but they might come back to collect. Ijzerboeren are mostly looking for copper and aluminum, which isn't magnetic 🤷♂️
I think magneetvissers are mostly just curiously looking for adventure and discovery.
A guy I know decided to do this on a business trip in Tokyo and got arrested 😂
Not sure why he thought it would be a good idea to do this abroad.
That's nuts. Here in the Netherlands it can be extremely dangerous because of WW2 bombs. But I can't imagine why anyone would object to it in Japan