Magnet fishing, also called magnetic fishing, is searching in outdoor waters for ferromagnetic objects available to pull with a strong neodymium magnet. The hobby is a combination of environmentalism and treasure hunting. The magnets used are strong enough to remove large debris such as discarded bicycles, guns, safes, bombs, grenades, coins and car tire rims from bodies of water, but many who engage in the hobby are hoping to find rare and valuable items as well.