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xkcd #2944: Magnet Fishing
(imgs.xkcd.com)
Alt text:
The ten-way tie was judged a ten-way tie, so no one won the grand prize, a rare fishing monopole.
At worst, you're blown into a bunch of little bloody pieces.
But removing trash from the waterways I can get behind.
There isn't even one instance of an active bomb exploding... And magnet fishing is a pretty common thing. Plus generally people will call the police if they find something potentially dangerous or used in a crime. It's probably fine.
I remember watching a video where some people pulled a landmine out of a river and the cops were so annoyed to have to deal with it. Apparently this wasn't the first explosive that's come up out of that river and the cops basically blamed the people for pulling out another one.
the small chance of exploding just makes it more exciting!