While not as widely practiced as swordsmanship, samurai swimming was often a part of the bushi's training. It was natural for the Japanese warrior to develop swimming skills because Japan is surrounded by water where combat took place. Swimming and engaging an opponent in water reached a high level in certain clans of warriors. Depending on the speed, size, and depth of the water that was near a particular clan, different skills were developed. For example, some ryu of suiei-jutsu featured methods for swimming under water, while others focused on swimming in fast-moving rapids.
Combative swimming served various purposes, ranging from allowing the bushi to silently sneak up on an enemy, to floating for long periods, to fording strong rivers. Bushi needed to be able to swim while wearing armor, carrying flags, weapons, and banners. They needed to be able to use a bow and arrow while being almost submerged. Some ryu also featured grappling while in the water.
Combative swimming is seldom taught in modern-day Japan. Most of its contemporary practitioners are studying it as a means of recreation, as a way of maintaining their health, and as a method of disciplining their minds and bodies. But make no mistake, the small number of suiei-jutsu teachers that are still extant have not forgotten the martial origins of this rare art form, and they are also preserving it as an important cultural property of Japan.
Combative Swimming in Japanese