Ok....I had to look it up...

What is Magnet Fishing?
Magnet fishing is exactly what it sounds like: fishing, with magnets. Shocking, we know, but there really isn’t much more to it than that. You tie a rope onto a magnet and throw it in the water. If you’re lucky, it will stick to something that you can haul out and take home.
Have you ever dropped your keys down a drain as you got out of your car? Ever lost your favorite knife over the side of the boat while fishing? Plenty of people have, and that’s probably how magnet fishing got started. Since then it’s developed into a fully-fledged hobby that’s part environmentalism, part treasure hunting.
So, why do people do it? As we mentioned, part of the appeal is ecological. You can remove a ton of junk from the water, cleaning up your local river or making a lake safer to swim in. You can also enjoy the thrill of fishing without hurting any fish. The main draw, though, is the constant possibility of finding sunken treasure.