Nihon eiho (Japanese style of swimming) (日本泳法)

Nihon eiho, also called Koshiki eiho, is a Japanese traditional style of swimming.
It includes not only the normal swimming, but swimming in armor and combat techniques in the water as a military art, such as fighting techniques in the water and firing a matchlock while treading water (Some schools also teach seamanship.)
These names are the ones given after the Meiji period, and the original names are 'suizyutsu,' 'suiren,' 'tosuizyutsu,' 'yueizyutsu,' 'syusuizyutsu,' etc.

They were swimming techniques for samurai to fight in the water and rivers, or to protect themselves, and were considered important as the necessary accomplishments of a samurai.

Same as the kobudo (classical material arts), many of them were developed in the Edo period. However, those started in the late Edo period were not always practical, and considered that a school could not cope with all the different forces of water, and so in 1932, Japan Aquatic Competition Federation (forerunner of Japan Swimming Federation) selected important ones from the conventional styles, designating them to be 'standard styles of swimming' including competitive styles focused on speed, setting them as a compulsory subject at schools. They were 12 kinds such as the crawl, backstroke, breaststroke, "noshioyogi" (sidestroke), "katanukite" (one arm swing stroke), "aori-hiraoyogi" (breaststroke with swinging legs), "nukite" (swing stroke), "tachioyogi" (treading water), "moguri" (diving), "ukimi" (floating), "sakatobi" (headlong dive), and "tachitobi" (standing dive), and the leg motions were 4 kinds such as "bata-ashi" (kick), aori-ashi" (swing), "kaeru-ashi" (frog kick), and "humi-ashi" (tread). At present there are 12 schools authorized by the Japan Swimming Federation.

There are some techniques as in common with synchronized swimming, and it was a group of Nihon eiho who introduced the synchronized swimming to Japan since they noticed the commonality between the two.

Meetings for Japanese swimming style are held every spring in various parts of the country, and Japanese Martial Arts Swimming Championship is held every summer.

Nowadays, in most cases, regular swimming pools are used to learn this style of swimming, and swimmers do not wear traditional "hundoshi" (loincloth) unless they swim in a special event. Both men and women wear regular swimsuits for competitive swimming. Japanese swimming style is not an 'old' style but is a still useful and beneficial one in present time, and there is no purpose to be overly nostalgic.