Mizugumi were wooden contraptions used by the ninja to walk across the surfaces of moats and ponds. Mizugumi look like flat wooden donuts made up of four curving slices of wood lashed together with strips of leather. The ninja would strap his feet to a leather thong in the center of each "donut." Like snowshoes, the mizugumi served to distribute the ninja's weight over a larger surface area, thus allowing him to walk across the surface shallow, marshy water with the aid of a bamboo pole. It is a common myth that the ninja could use mizugumi to walk across any body of water, but in reality it would have been impossible to use mizugumi in a deep, clear lake or a swift moving river, although they were ideal for traversing the muck-filled moats that surrounded Japanese Castles.