[1] Competition is divided into two classes: swimming pool and long distance (also called open water).

[4] Long distance sites include both the sea and natural water bodies such as freshwater rivers and lakes.

Site selection criteria include 'low current and tides' and water quality 'appropriate for swimming' as certified by a local authority.

Swimmers must remain on the surface of the water at all times for the duration of the race except when starting or make a turns at the end of a swimming pool where an immersion over a distance of 15m is permitted.

[1] Immersion finswimming with breathing apparatus (also known by its acronym, IM, immersion, and scuba finswimming), is underwater swimming using mask, monofin and underwater breathing apparatus (open-circuit air scuba) conducted in a swimming pool.

[5] Bi-fins (also known by its acronym, BF or as 'stereo-fins') is swimming on the surface of the water with mask, snorkel and a pair of fins using a crawl style.

It is reported that BF was introduced in 2006 to provide the opportunity for competition by swimmers who cannot afford to purchase a set of monofins.

Swimmers must remain on the surface of the water at all times for the duration of the race except when starting or make a turns at the end of a swimming pool where an immersion of a distance of 15m is permitted.

Monofins have a maximum size which can be checked by the use of a template while bi-fins must be one of the brands certified (i.e. homologated) by CMAS.

[10] Luigi Ferraro, Italian diving pioneer, is reported as organising the first fin-swimming competition in the sea during 1951 followed by a 100 kilometres (62 miles) ocean swim in 1955.

[11][13][14] The arrival of the monofin in the early 1970s lead to the breaking of all world records by the end of the decade due to the improved performance possible when used in lieu of bi-fins.

[citation needed] It has been recorded that sports swimmers tend to approach finswimming with preconceptions on technique, which can limit their success.

[19] As of June 2015, national federations in the following countries and territories have affiliated with the commission: Algeria, Argentina, Armenia, Austria, Australia, Belgium, Belarus, Canada, Cameroon, Cape Verde, Chile, Colombia, Cuba, China, Croatia, Cyprus, Czech Republic, Denmark, Ecuador, Egypt, Estonia, Finland, France, Germany, Great Britain, Greece, Hungary, Hong Kong, Indonesia, Italy, Japan, Jordan, Kazakhstan, Kenya, Korea, Kuwait, Kyrgyz Republic, Lebanon, Luxembourg, Libya, Mexico, Marianas, Montenegro, Netherlands, Palestine, Peru, Philippines, San Marino, Saudi Arabia, Serbia, Singapore, Slovakia, Slovenia, Spain, Switzerland, Syria, Russia, Tunisia, Turkey, Taiwan, Thailand, United Arab Emirates, United States of America, Venezuela and Vietnam.

[22] Since 2006 This is an annual event which was first held in 2006 and consists of a minimum of three rounds including a final all known as meetings which are attended by swimmers from clubs affiliated to a CMAS national federation.

Races are held in both swimming pool and open water sites for individuals and clubs in the age groupings of senior and junior for both male and female.

[23] This is an annual swimming pool-based event for junior national teams for both male and female swimmers.