One mile in icy water

The Ice Mile is the first and most prestigious individual challenge of the International Ice Swimming Association (IISA): one British mile in water of 5 °C or below, in a swimsuit, cap and goggles. It is not a race but a personal challenge that can be attempted in any icy water on earth, as long as every IISA rule is met.

Status: 10 October 2026. This page summarises the IISA Swimming Rules and Regulations (effective from 1 December 2025) and the Medical and Safety Regulations (effective from 1 November 2024). The official, current IISA guidance always applies, and the rules may change. In case of doubt, the rules themselves decide.

• 1609 m

  At least one British mile. Longer swims also count as an Ice Mile and are recorded with the distance swum.

• ≤ 5.0 °C

  Measured with at least three digital thermometers no more than 30 minutes before the start. Every thermometer must read 5.0 °C or lower; if even one reads 5.01 °C or higher, it is not acceptable. The water must meet this requirement for the entire duration of the swim.

• 20–45 minutes

  The typical duration. There is no time limit, but the risk rises sharply after 30 minutes.

• 3 officials

  An IISA Observer and a Witness (both IISA L1 accredited), plus at least one Medical Officer on site.

• Ask those who have done it

  The best preparation is to talk to people who have already swum an Ice Mile: they can tell you what it feels like, how they trained, and what team and venue you need. See the list of Hungarian Ice Mile swimmers, reach them through the teams and groups, or write to us and we will help you get in touch.

First steps

1. 1

   Qualify

   Complete a shorter, officially observed qualifying swim and upload it to your IISA BIO. Details

2. 2

   Medical clearance

   The IISA medical form and a 12-lead ECG, no older than 12 months. Details

3. 3

   Venue and team

   Outdoor, naturally cold water, an accurately measured course, an Observer, a Witness and a Medical Officer. Details

4. 4

   Rules

   Attire, start, timing, unassisted swimming, photos and videos. Details

5. 5

   Ratification

   After the swim, apply to IISA online; until approval it is a "successful Ice Mile attempt". Details

Qualification requirements

You may only attempt an Ice Mile after completing a shorter distance in icy water. The qualifying swim must be uploaded to your IISA BIO; without it the Ice Mile cannot be approved.

• A qualifying swim is valid for 24 months.
• The qualifying swim's Observer must also be a valid IISA L1 accredited official.
• For 1000 m or longer you must be at least 18 years old on the day of the swim.
• At least 6 hours must pass between two Ice Mile attempts, with a doctor's approval.

Medical requirements

• The documents: the IISA medical form signed by your own doctor and a 12-lead ECG, both no older than 12 months. When they lapse and which specialist reports you need: Health requirements.
• On the day: you show the documents to the Observer and the Medical Officer. The Medical Officer checks your heart rate, blood pressure and temperature before the swim; their decision is final.

Venue and team

• The water

  Outdoor, naturally cold water: open water, a river or an outdoor pool. At least 0.9 m deep, with laps or legs of at least 25 m.

• Measuring the course

  With a tape measure, handheld GPS or laser; smartwatches and phones are not acceptable. You must be 100% sure the course is at least 1609 m, measured to the centre of the turn buoys.

• Water safety

  Without water support you stay within 5 m of land, with a kayak or SUP within 25 m. A motor boat stays within 10 m of you.

• Recovery area

  No more than 250 m and 5 minutes on foot from the finish.

• The team

  An IISA Observer and a Witness (IISA L1), plus at least one Medical Officer, who cannot be the Observer. Everyone wears identification.

• IISA L1 Observer

  An official accredited by IISA and properly trained, who knows the safety protocols and the rules of the swim. They check the preconditions (qualification, medical documents, water quality, course length, temperature, etc.) and may stop the swim at any time. The Witness must also be L1 qualified. Contact them well before your Ice Mile, tell them you intend to swim it, and introduce yourself so that they know everything important about you (planned stroke, duration, distance, etc.). The list of L1 officials, by country, is on the IISA website.

• Second

  An Ice Mile also needs a second who looks after you alone during the swim. Your second's duties in detail

Rules

• Attire

  One standard swimsuit, one silicone or latex cap, one pair of goggles. A waist belt is mandatory on every IISA swim. More in the Equipment section.

• During the swim

  Any stroke is allowed. The swim is unassisted: no standing, walking, deliberately touching the ground, and no eating or drinking. Hyperventilating before entering the water is prohibited.

• Start and timing

  Three calls: clothes off, into the water, then "Go" at the start point. Time runs from the start call (not from walking into the water) and is taken with a device accurate to the second.

• Temperature

  At least three waterproof digital probe thermometers (±0.1 °C), 12.7–50.8 cm deep. Laser and infrared thermometers and watches are not acceptable.

• Evidence

  10 high-resolution photos (course, thermometers, time, attire, start, finish, recovery, water safety, team) and unedited, public YouTube video. Wind speed and air temperature must also be recorded.

The exact requirements are in the Ice Mile check list; go through it with your team in advance.

Ratification

1. 1

   Before the swim

   You sign the Ice Mile indemnity (mandatory). For an Extreme Ice Mile or a long distance swim, you must also notify IISA of your intention by email.

2. 2

   After the swim

   You apply to IISA online. The documents: the check list and the observation form.

3. 3

   The Observer and the Witness

   They check and verify the swim details online.

4. 4

   Until approval

   The swim must be called "a successful Ice Mile attempt, subject to IISA ratification".

5. 5

   After approval

   You receive a digital certificate and are entered in the IISA Ice Mile records.

Extreme Ice Mile

An Extreme Ice Mile is a higher-risk Ice Mile attempt. It counts as one if at least one of the following applies:

• ≤ 2.0 °C

  The water temperature is 2.0 °C or colder.

• ≤ −15 °C wind chill

  The wind chill is −15 °C or lower.

• ≥ 2.00 km

  The attempted distance is at least 2.00 km.

• ≥ 2440 m altitude

  The venue is at 2440 m or higher.

What applies on top of that:

• Qualification: under the IISA qualifying table, 1 mile swum in water of 0.0–5.0 °C; a swim in warmer water does not qualify.
• Recommended background: IISA recommends an Ice Mile within the past 18 months.
• Over 2 km: IISA must be notified at least 48 hours in advance ([email protected]), and IISA decides whether the swim may go ahead.
• IISA's discretion: IISA may reject the attempt, ask for additional qualification, safety measures or information, and may approve the Observer.

Long-distance ice swim

In the IISA rules, the "ice marathon" is the Long Distance Ice Swim: at least 3.0 km in water of 5.0 °C or below, under IISA rules. On top of the Ice Mile requirements:

• Notice: at least 7 days in advance, email IISA ([email protected]) with the details of the intended attempt.
• Qualification: per the IISA qualifying table; IISA recommends an Ice Mile within the past 18 months.
• Attempt details: distance, location, expected water temperature, long-distance ice swimming background, safety plan, the nearest medical facility and a medical emergency plan.
• Doctor on site: a doctor must be on site throughout, observing the swimmer from the start to the end of recovery.
• One swimmer at a time: only one swimmer may attempt at a time.
• Recent medical: the IISA medical form and ECG must be within three months of the attempt (12 months for an Ice Mile).
• Indemnity: the Ice Mile indemnity is required here too.
• During the attempt: a full video from undressing to recovery, split times at least every 500 m, and proof of course measurement and distance with video and photos.
• IISA's discretion: IISA may decline to support an attempt; if the swimmer goes ahead anyway, the swim cannot be linked to IISA and will not be ratified.

Official documents

This page is based on the IISA Swimming Rules and Regulations, the Medical and Safety Regulations, the medical assessment form, the Ice Mile check list and the observation form. They are listed, with their effective dates and the date of our last check, on the Documents page.