Do you know about magnet fishing? I just heard about it for the first time today. It is metal detecting with a big magnet tied to a rope you throw into water and then drag through it to find anything metal enough to stick to your magnet. I think that is another form of exploration, seeing what you can find basically. I'd prefer it to actual fishing, trying to catch fish. But, either way there is a lot of patience and stuff you don't keep. Magnet fishing benefits the water systems. If, people don’t just throw all the junk right back into the water. People I have seen (Random Andrew in video posts) magnet fishing seem to keep a bucket to throw in the bits of wire, nails, and assorted bits they find. I’d be hoping to find old coins but I didn’t see much of that turning up in the video posts I watched today. Guns, which have to be turned into the police, and a metal sign were more interesting than bits of wire.
There is also the problem of your magnet getting caught on debris and the chance you might lose it. I think most of the time it can be saved one way or another. But, there will be that less lucky day when you can’t pull it out again, or your rope snaps. This is a good time to learn a few good sailor knots.
Expect to get wet. I’d bring a change of clothes and foot wear for walking in rivers, streams and generally wet places.