Minecraft wiki entry for Drowned_farming, associated text: If you are in a situation where there isn't any way to build an iron golem farm for iron (say you are playing an island survival game and there is no village within thousands of blocks), or a gold farm for gold, you feel like you've mined out your area, and you no longer need drops from drowned, you can use a flooded dungeon farm to harvest iron and gold from the zombies. It's a slow but effective way to get iron and gold ingots. Accumulate gold faster than iron, however.