Minecraft wiki entry for Underwater_home, associated text: Using sponges is a great way to dry out a big volume of water. Sponges can be found inside ocean monuments. You can dry out ocean monuments using the methods above until you find some sponges; this is more time-consuming than swimming but eliminates the risk of drowning in case you get lost in the monument. When a sponge is placed, it will soak up water in a 9×9×9 volume centered on itself, and become a wet sponge. Bring enough wood and cobble down with you to make a crafting table and furnace to dry the sponges.