type approved for use subject to meeting minimum and maximum requirements in tube length and internal diameter. Fins are also regulated by international rules. 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. Underwater breathing apparatus is restricted to open circuit scuba using compressed atmospheric air as the breathing gas. The use of oxygen enriched mixtures is forbidden. Cylinders are limited by maximum cylinder pressure rating of 200 bar and a minimum cylinder capacity of 0.4 litres. While there are no requirements for regulators, swimmers appear to be free to modify these to remove any unnecessary parts. Garments such as swimsuits, swim caps and wetsuits, and the use of logos printed on these garments and the equipment is also subject to the requirements of the international rules. Age groupings and associated restrictions The following age groupings and associated restrictions for both men and women are mandated by the International Rules. Origins and history The sport developed in Europe following the ready availability of the first rubber fins during the 1930s. Luigi Ferraro, Italian diving pioneer, is reported as organising the first fin-swimming competition in the sea during 1951 followed by a ocean swim in 1955. The first competition in the Soviet Union was held during 1958. The first European Championship which was a multi sport event involving both finswimming and underwater orienteering was held under the title of the First European Championship of Subaquatics Technical at Angera, Italy in August 1967. The specific finswimming events were races over the distances of 40m and 1000m which are reported as using either surface swimming techniques or respectively apnoea and immersion techniques. In 1969, the first European Finswimming Championship to be separate of underwater orienteering was held in Locarno, Switzerland. The first World Championships were held in Hanover, Germany during 1976 followed by the inclusion of the sport in the inaugural World Games in Santa Clara, California, USA during 1981. In 1988, the first World Long Distance Championship was held in Paris, France followed in 1989 by the first World Junior Championship in Dunaújváros, Hungary. 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. In 2007, the first