I've been catching up on some old episodes of the Discovery Channel's show "Mythbusters," and ran across one with a definite Asian historical flair.
In Episode 78, which was all about ninja myths, Mythbuster Adam Savage tried to build a pair of mizugumo - water-walking shoes. The shoes, which work on a similar principal to snowshoes, are made of circles of laced-together wood, and are meant to distribute the wearer's body-weight across a wider surface area. They are named for the insects we call "water-striders" in English.
Mr. Savage took his mizugumo to a pool, took one step, and sank like a stone. As it turns out, this particular design was intended more for crossing muddy paddy fields than for actually walking on water. Some ninja reported also used air-filled bladders as flotation devices. They certainly didn't use Styrofoam pontoons, which was the Mythbuster's second idea.
It seems to me, though, that the easiest way to cross a Japanese castle moat would be to swim.
Photo of Adam Savage by John G. Heller / Getty Images.