Although it is impossible to walk unaided on water in its natural state, adding cornstarch to it creates a substance called "oobleck," which behaves as a solid under pressure. The only caveat is that one has to keep moving in order to avoid sinking.
By adding enough cornstarch to a swimming pool in this way, people have managed not only to walk on water, but to run, dance and even play soccer.
Ancient Japanese ninjas are believed to have "walked" on water when their missions called for it, by using a contraption called a "mizugumo" (or "water spider"). This device consisted of four wooden floats joined together in a circular formation around a central board. By attaching one of these devices to each foot, ninjas were able to cross bodies of water with the aid of an oar.
Performance artists and street magicians, such as Dynamo, are able to create the illusion of walking on water. Although they guard their secrets closely, it is plausible that the trick is achieved by hiding a platform just below the water's surface. When Dynamo performed this stunt on the Thames in London, some passing canoes appeared to collide with something solid beneath the surface of the water.