If you consider yourself an expert at fishing you might like to try fishing for bikes in Amsterdam. I never knew that there were so many bikes that had to be fished out of the canals in Amsterdam but apparently they are thrown in by hooligans or discarded by owners on a regular basis. It appears that the canals are fairly shallow so the 12,000 to 15,000 bikes that are recovered each year could quickly fill up the canal. I would imagine that the claw used to fish for these bikes is magnetized.