CMAS Finswimming Rules 2025/02 (In Force from 2026): A Plain-English Guide for Indian Athletes, Parents and Coaches

Every serious finswimming athlete in India eventually runs into the same question: "What do the rules actually say?" The CMAS Finswimming Rules, Version 2025/02 (approved by the CMAS Board of Directors as BoD 238 on 08/11/2025) have been in force since 1 January 2026. They govern every CMAS-sanctioned finswimming competition, and they are the rulebook followed by the Underwater Sports Association (India) — USAI, India's CMAS-affiliated Underwater Sports Federation of India.

The full document is 31 pages. This guide pulls out the parts that matter most to athletes, parents, coaches, and officials in India, in plain English.

Download the official rulebook: CMAS Finswimming Rules 2025 (PDF) on cmas.org

What Counts as Finswimming?

The rules define finswimming as progression with a monofin or with two fins, either on the surface or underwater, using the swimmer's muscular force only. No support or mechanism of any kind, even a muscle-powered one, is permitted in competition.

Age Groups

CMAS uses the following age groups:

  • Senior (Category A): 18 years and over
  • Junior B: 16–17 years
  • Junior C: 14–15 years
  • Junior D: 12–13 years
  • Junior E: 11 years or less (the "pre-competition" group)
  • Masters: individual groups of M30+ (30–39), M40+ (40–49), M50+ (50–59), and so on in ten-year bands

Masters relays are grouped by the sum of the four swimmers' ages: R140 (140–179), R180 (180–219), R220 (220–259), and R260 (260 and above).

National events such as the All India Finswimming Federation Cup may split the youngest swimmers into additional sub-groups, so always check the circular for the specific event.

Minimum Ages for International Events

  • Under 12: may compete only in CMAS-calendar events that specifically provide for Category E, and cannot swim in a higher category in individual events
  • 12 years: World Cup
  • 14 years: World, Continental, or Zone Junior Championships
  • 15 years: World Cup (senior classification) and World, Continental, or Zone Senior Championships

Rules for Masters Swimmers

Masters swimmers must compete only in their own age category. Every member of a Masters relay must be at least 30, and a Masters swimmer may swim only one relay per session. Withdrawals must be communicated by the technical meeting at the latest; an untimely no-show means the swimmer cannot take part in the remaining events of that session.

The Four Pool Disciplines, and Their Technique Rules

Surface Finswimming (SF)

The swimming style is unspecified, but the swimmer may stay immersed only within 15 metres after the start and after each turn. Outside that zone, part of the swimmer or equipment must stay above the surface. A snorkel is used throughout.

Apnoea Finswimming (AP)

Swum in swimming pools only, without a snorkel, with the face submerged for the whole distance. Apnoea races are limited to 50 m, and Category E swimmers cannot compete in apnoea.

Immersion Finswimming (IM)

Swum with compressed-air breathing apparatus only. The swimmer may not change or abandon the apparatus during the race, the face must stay submerged, and the breathing equipment must never touch the pool walls or finish touchpads. Abuse leads to disqualification.

Bi-Fins (BF)

The style is crawl with a snorkel at all times. Dolphin kick is allowed only within the 15-metre zone after the start and each turn. At the start, the swimmer's fins must be on a parallel line at the front of the starting block.

Open Water Rules

In open water, underwater swimming is not allowed, a snorkel is mandatory, and bi-fins swimmers may use any style. The Style Judge shows a yellow card as a warning and a red card (disqualification) for a repeat offence. Deliberately obstructing another swimmer earns a yellow card, then red if repeated. Violent behaviour such as a direct blow, or pulling a swimmer backwards, earns a direct red card.

Safety requirements for the course include at least one safety boat for every ten swimmers, buoys no more than 500 m apart, and a maximum lap length of 1 km at world and continental championships. If the water temperature is below 14°C, a neoprene suit is mandatory, and the Technical Delegate can stop a race after 50% of the distance for safety or weather reasons.

Equipment: Why "CMAS-Certified" Matters

This is the section every athlete and parent should read twice.

  • Monofins must be certified by CMAS, shown by an official CMAS sticker on the blade. Certified monofins are obligatory for CMAS championships, World Cups, international competitions, and record certification.
  • Bi-fins must also be CMAS-certified for bi-fins races at those same events. Fins must be used as sold: cutting, modifying, or adding protuberances is forbidden, and nothing may be stuffed into the foot pocket.
  • Neoprene boots are forbidden. Foot protection in thin neoprene or plastic is allowed.
  • Snorkels must be circular in section, with an internal diameter of 15–23 mm and a length of 430–480 mm, with no fairings or attachments.
  • Swimsuits: for pool events, competitive swimsuits must be homologated by CMAS and carry a CMAS QR code, which must be firmly attached and registered in the CMAS database after purchase. Only one sportswear item is allowed, and one or two swim caps may be worn.
  • Immersion cylinders: compressed air only, a minimum of 0.4 litres (1.0 litre for 200 m and 400 m immersion), a maximum pressure of 200 bar, a hydrostatic test within the last two years, and each cylinder presented empty at the checking meeting.
  • Not allowed in pool competition: watches, any kind of body tape (including Kinesio tape), and any object placed on the starting block other than an approved mat.

Swimmers with non-conforming equipment will not be admitted to the starting block, and irregularities found after a race lead to disqualification. Several of these clauses, including the swimsuit QR code requirement, are highlighted in yellow in the published PDF, so read them closely in the original.

This is exactly why USAI encourages athletes to buy CMAS-approved equipment from the start, rather than discovering at a championship that their gear is not accepted.

Competition Categories and Entry Limits

CMAS classifies its competitions as:

  • Category A: World Championships and Continental/Zone Championships
  • Category B: World Cups (seniors, juniors, masters), certain European Cup groups, and university competitions
  • Category C: all other events registered in the CMAS calendar

World and Continental pool championships alternate every two years (World in even years, Continental in odd years). In pool championships, each country may enter no more than two swimmers per distance and one relay team. In open water championships, each country may enter up to four swimmers per distance (two in the elimination race) and one relay team per category.

All CMAS competitions follow the WADA and CMAS anti-doping rules.

For the 400 m IM, 800 m SF, and 1500 m SF at World and Continental championships, national federations must send official protocols of their national selection competitions to CMAS within two weeks. Without them, enrolments can be cancelled. This is one reason accurate, properly documented national championships, such as those run by USAI, matter so much for selection.

Masters Championships

The CMAS Masters programme in the pool includes 50 m AP, BF and SF, 100 m and 200 m BF and SF, 400 m BF and SF, and 800 m SF, plus the 4x50 m SF and 4x100 m SB mixed relays. A Masters swimmer is limited to six individual race entries. In open water, the events are 1 km and 3 km in both BF and SF, plus a 4x1 km SB mixed relay.

Pool and Timing Standards

For CMAS championships the pool must be 50 m long, at least 21 m wide and 1.80 m deep, with at least 8 lanes and water temperature between 25°C and 28°C. Timing is automatic to 1/100 of a second, with fully automatic touchpad timing having priority over semi-automatic or manual timing.

Race Procedure and Disqualifications

  • Seeding is based on each swimmer's best time in the last 12 months, submitted on the entry form
  • Start: a series of brief whistles tells swimmers to prepare (they have 1 minute 15 seconds), a long whistle puts them on the block, and the starter commands "take your marks"
  • False start: a swimmer who moves before the signal is disqualified
  • Common disqualifications: crossing lanes or hindering another swimmer, exiting over the touchpads, pulling on the lane rope, and losing or abandoning part of the equipment during a race (Masters swimmers are exempt from the equipment-loss rule)
  • Standing on the bottom does not disqualify a swimmer by itself, but walking is not allowed
  • Relays: names and order must be submitted before the session, mixed relays are two men and two women swimming man–woman–man–woman, and a change to the fixed order means disqualification
  • Withdrawals from a final must be announced within 30 minutes of the finalists being announced. At CMAS Championships, unexcused no-shows result in fines for the swimmer's federation: €100 for a heat and €250 for a semi-final or final

Officials and Records

Pool events need a Chief Judge, Chief Secretary, Starter, Prestart Judge, Chief Timekeeper, timekeepers, two Finish Judges, two Style Judges, Turning Judges, a Speaker, a Master of Ceremonies, and a Doctor. The presence of at least one doctor is compulsory at all finswimming events.

CMAS homologates records only in a 50 m pool with electronic timing to 1/100 of a second, with an application signed by the Chief Judge. National records are recognised by CMAS only when they are officially communicated by the national federation.

What This Means for Indian Finswimmers

For athletes training and competing through USAI, the practical takeaways are simple:

  1. Know your age group by birth year before you register.
  2. Use CMAS-certified fins and homologated swimsuits if you aim for international events.
  3. Learn the 15-metre rule and the technique rules for your discipline. Technique disqualifications are avoidable.
  4. Compete through the CMAS-affiliated federation, because selection, protocols, and records all flow through it.

You can read more about USAI, explore finswimming training in India, or register for the National Finswimming Championship.

A Note on Reading the Rulebook

This blog is a summary for convenience. For exact wording, especially on equipment specifications, disqualifications, and records, always refer to the official document: download the CMAS Finswimming Rules 2025 from cmas.org. The rules are also the single best way to confirm what a genuine CMAS-affiliated event looks like, and you can always verify affiliation at cmas.org.

Stay Connected

For more guides, circulars, and news from India's underwater sports and finswimming community, keep visiting underwatersportsindia.com, the official website of the Underwater Sports Association (India), USAI.