12 Surprising Rules Marathon Swimmers Must Follow in the 2024 Paris Olympics

Mar. 15, 2025

Team USA’s Mariah Denigan takes a drink as she competes in the marathon swimming women’s 10k on day 13 of the 2024 Paris Olympics.Photo:Sarah Stier/Getty

Sarah Stier/Getty

Let’s dive in, shall we?

Swimmingisamong the most-watched sportsat the Summer Olympics each year, between the high-energy sprinting races and the beautiful artistic swimming events that draw viewers poolside as the competition unfolds.

Marathon swimming at the 2024 Paris Olympics starts and ends at the Pont Alexandre III in the iconicSeine River, where athletes cover 10 kilometers (or approximately 10.6 miles) in its open waters. There are two events, one for women (which took place on Aug. 8) and one for men (which takes place on Aug. 9).

You may be wondering why the disciple is titled “marathon swimming” if the distance isn’t 42 kilometers (or 26.2 miles) like running races. That’s because the time it takes marathon swimmers to complete the race is similar to the time it takes runners to finish road marathons (approximately two hours).

In contrast to pool events, open water swimmers go head to head with more than just their fellow competitors; they’re also up against Mother Nature. The endurance athletes must combat the unpredictable, uncontrollable obstacles that come their way, from weather to changing currents.

Read on for the most surprising rules you didn’t know marathon swimmers must follow at the 2024 Paris Olympics.

Marathon swimmers must race in open water

Athletes compete in the marathon swimming women’s 10k race on day 13 of the 2024 Paris Olympics.Clive Rose/Getty

Clive Rose/Getty

Athletes competing in marathon swimming must race in open water environments such as the sea, rivers and lakes. The 10km course for the 2024 Paris Olympics is held at in the Seine River.

Swimming in open water requires a different set of skills, in comparison to athletes who race in pools. Physical and mental strength is necessary to push through the lengthy distance of the course and adapt to the unpredictable obstacles of Mother Nature.

Marathon swimmers must wear a swim cap with country representation

Team Netherland’s Sharon van Rouwendaal takes a breath during the marathon swim at the 2024 Paris Olympics.Clive Rose/Getty

World Aquaticsis the governing organization of rules and regulations for Olympic marathon swimming. According to its official handbook, the open water race will commence “with all competitors wearing an approved swim cap.”

The organization rules it “mandatory” for the cap to display the “national-three letter code” on each side. In addition, swim caps “may also display the swimmer’s national flag or the swimmer’s name.”

Specific logo dimensions on the caps must also be met. “Displaying the competitor’s name is not compulsory,” World Aquatics states.

Marathon swimmers must wear specific swimsuits

Italy’s Giulia Gabrielleschi stands beside the water ahead of the women’s marathon swimming at the 2024 Paris Olympics.Image Photo Agency/Getty

Image Photo Agency/Getty

The swimsuits marathon swimmers wear are different than those who race in pools. According to World Aquatics, there are several requirements that must be met.

“For open water swimming competitions with water temperature from 18°C and above, swimsuits (men and women) shall not cover the neck, nor extend past the shoulder, nor extend below the ankle,” the organization states.

The use of wetsuits “is compulsory” for open water swimming competitions “in water with temperature below 18°C,” World Aquatics continues. “Wetsuits are not permitted in open water swimming competitions in water with temperature 18°C and above.”

Similar to the swimsuits, wetsuits must meet a specific cut to be worn in competition. For men and women, the organization states that wetsuits “shall completely cover torso, back, shoulders and knees.” It reads, “They shall not extend beyond the neck, wrists and ankles.”

Swimmers are not permitted to wear any device that “may be an aid to their speed, endurance or buoyancy.” Approved swimsuits aside, athletes are allowed to wear a maximum of two swim caps.

Plus, nose clips and earplugs may be used.

Marathon swimmers must be numbered on their skin

Team Australia’s Moesha Johnson and Team Italy’s Ginevra Taddeucci hug after winning silver and bronze medals in the marathon swimming women’s 10k race on day 13 of the 2024 Paris Olympics.Clive Rose/Getty

In order to identify and track the swimmers in the water, the competitors must be visibly numbered on their arms, upper backs and hands. The numbers are to be arranged vertically on their arms and horizontally on their upper backs and hands.

“For competitors with darker skin and full body wetsuits, a white marker pen will be required,” World Aquatics states.

Marathon swimmers must wear two microchip transponders

Team Netherland’s Sharon van Rouwendaal seen swimming with her microchip transponder on her wrist during the women’s marathon swimming event at the 2024 Paris Olympics.Andre Weening/BSR Agency/Getty

Andre Weening/BSR Agency/Getty

It is mandatory for marathon swimmers to wear a microchip transponder on each wrist throughout the race. These are lightweight, waterproof timing devices with GPS capabilities to track the competitors.

“If a competitor loses a transponder, the race judge or other authorized official will immediately inform the chief referee who will instruct the responsible official on the water to issue a replacement transponder,” World Aquatic states.

“Any competitor who finishes the race without at least one transponder will be disqualified.”

Marathon swimmers must start from a pontoon

Swimmers dive into the Seine River at the start of the women’s marathon swimming 10k race at the 2024 Paris Olympics.Martin Bureau - Pool/Getty

Martin Bureau - Pool/Getty

Marathon swimming at the 2024 Paris Olympics will begin with a mass start from a pontoon at the iconic Pont Alexandre III below its famed arch bridge that spans the Seine River.

“Take your marks” is the starter’s commands, when all swimmers will place at least one foot on the edge of the fixed platform to ready themselves before diving in head first. “The start signal shall be both audible and visual,” states World Aquatics.

Marathon swimmers are allowed to stand during the race

A view of the women’s marathon swimming event at the 2024 Paris Olympics.Image Photo Agency/Getty

While stopping mid-race is unlikely (these people are after gold!), marathon swimmers are allowed to stand on the bottom of the river mid-swim. However, World Aquatics states they “may not walk or jump.”

Drafting techniques are allowed in marathon swimming

Team Italy’s Giulia Gabbrielleschi seen swimming in the women’s marathon swimming event in the 2024 Paris Olympics.Clive Rose/Getty

While all swimmers use the freestyle stroke during the marathon race, they adopt various strategies to perform their best in the water. Among the most popular strategy adapted to cope with changing currents and tides while maintaining their speed is thedrafting technique.

Escort vessels are allowed in marathon swimming

A view of the competitors along with their escort vessels during the women’s marathon swimming event at the 2024 Paris Olympics.Clive Rose/Getty

Swimmers are allowed the accompaniment of an escort vessel — a person or group in a boat, kayak, paddle board or surfboard — during the marathon swim, to help aid with protection during the open-water swim.

But it’s solely a safety measure: World Aquatic prohibits “pacing or slip streaming” from the escorts.

“Escort safety craft shall maneuver so as not to obstruct or place them directly ahead of any competitor,” the organization states. The competitors can risk disqualification if their vessel doesn’t comply with the rules.

Incidental contact is allowed in marathon swimming

Team USA’s Katie Grimes and Team Spain’s Maria de Valdes Alvarez compete in the women’s marathon swimming event at the 2024 Paris Olympics.Clive Rose/Getty

Since there are no lanes separating competitors in marathon swimming, contact with other athletes is inevitable. The sport can get aggressive, with accidental kicks and jabs thrown at each other, especially at the mass start.

Therefore, “incidental contact between swimmers is permitted,” according toNBC Olympic rules.

Swimmers are allowed to fuel up during the race

Support crew extends hydration bottles to their athletes during the women’s marathon swimming event at the 2024 Paris Olympics.Martin Bureau - Pool/Getty

Swimming 10km at an extremely fast pace is undeniably exhausting, and swimmers need to refuel several times throughout. Coaches are permitted to attach water or energy drinks to a pole for the athlete to collect mid-swim.

“Feeding poles are not to exceed 5m in length when extended. No objects, rope or wire may hang off the end of feeding poles except,” per the organization. “National flags” are an exception, but they may not exceed a specific size requirement when attached to the pole.

Swimmers must touch the wall to finish the race

Team USA’s Katie Grimes reacts after competing in the women’s marathon swimming event at the 2024 Paris Olympics.Sarah Stier/Getty

Swimmers end the race where they started just below the Pont Alexandre III. To signify completion, competitors must touch the vertical wall to finish the race.

“Any competitor who does not touch the vertical wall will be disqualified,” World Aquatics states. Swimmers will also be disqualified if they finish the race “without at least one transponder” on their wrist.

source: people.com