Cold water shock and hypothermia: what to do

Last verified: 14 October 2026

Step by step

1. Float first, don't swim

   Cold water makes you gasp and breathe very fast. Fight the urge to swim or thrash. Tilt your head back with your ears under water, spread your arms and legs, and float until your breathing settles.[1][2][3][5]

2. Keep your mouth and nose clear

   A lifejacket holds your mouth and nose out of the water while you get your breathing under control. If you have no lifejacket, hold on to anything that floats.[6][4]

3. Call for help once you can breathe

   When your breathing is under control, shout, blow a whistle or use your radio, phone or beacon to call for help.[3]

4. Use the next 10 minutes to get out

   Your arms, legs and fingers will weaken over roughly the next ten minutes. Use that time to climb back aboard or onto anything floating, and get as much of your body out of the water as you can.[7][12]

5. Swim only if safety is close

   Swimming makes you lose heat faster. Only swim to reach other people, a boat or shore that you are sure you can reach. Don't swim to keep warm.[8][14]

6. Alone and can't get out: HELP position

   Keep still to save heat. Cross your arms tightly over your chest and draw your knees up towards them, with your head out of the water.[9][11][14]

7. With others: huddle

   Huddle together with your chests close, arms around each other's backs and legs together. This slows heat loss and keeps the group together for rescuers.[10][22]

8. After rescue: lift gently and lie them down

   If you can, lift a cold casualty out of the water lying flat rather than upright. Handle them gently and get them into a warm, dry, sheltered place as fast as possible; their core temperature can keep falling after rescue.[15][13]

9. Warm them slowly

   Remove wet clothing and wrap them in a blanket, sleeping bag or dry towel, covering the head. If they are fully awake, give a warm non-alcoholic drink and some sugary food.[17][19]

10. Get medical help

    Hypothermia is a medical emergency that needs hospital treatment. Call the local rescue or emergency number.[20]

Don't

• Don't try to swim hard in the first minute. Let the cold shock pass first.[1]
• Don't swim just to keep warm. It speeds up heat loss.[8][14]
• Don't put a hypothermic person in a hot bath or rub their arms, legs, hands or feet.[18][21]
• Don't give alcohol to someone who is cold.[23]
• Don't lift a cold casualty upright if you can lift them lying flat.[15]

Before you sail

• Before you sail: wear a lifejacket or buoyancy aid. It greatly improves your chance of getting through the initial shock.[6][24]
• Before you sail: dress for the water temperature, not the air temperature.[25]
• Before you sail: treat any water below 15°C as cold water. That covers much of the year in many places.[26]
• Before you sail: carry a way to call for help on you, such as a VHF radio, PLB or EPIRB.[27]
• Before you sail: practise floating in a supervised place such as a swimming pool.[28]

Frequently asked

Sources

1. RNLI (2026-10-14): “Take a minute. The initial effects of cold water pass in less than a minute so don’t try to swim straight away.”
2. RNLI (Float to Live) (2026-10-14): “The best way to float is to tilt your head back with your ears submerged.”
3. RNLI (Float to Live) (2026-10-14): “Try to relax and breathe normally. You can gently move your hands and legs to help you stay afloat if you need to. Spread your arms and legs out to improve stability – and it's OK if your legs sink, we all float differently. Once your breathing is under control, call for help or swim to safety.”
4. US National Weather Service (NOAA) (2026-10-14): “If possible, utilize any floating objects to get out of the water.”
5. Transport Canada – Safe Boating Guide (TP 511E) (2026-10-14): “During cold shock, a person will take a sudden, deep gasp of air, then start to hyperventilate. This can be 600-1000% faster than normal breathing and it’s the body’s automatic response. This lasts about one minute.”
6. Transport Canada – Safe Boating Guide (TP 511E) (2026-10-14): “Wearing your lifejacket during this stage will keep you afloat, with your mouth and nose out of the water, so you can focus on your breathing.”
7. Transport Canada – Safe Boating Guide (TP 511E) (2026-10-14): “For the next 10 minutes or so, you will lose meaningful movement in your arms, legs and fingers. Focus on self-rescue. If that isn’t possible, find a way to keep your airway out of the water and wait for rescue.”
8. Transport Canada – Safe Boating Guide (TP 511E) (2026-10-14): “Only swim if you can join others or reach safety. Don’t swim to keep warm.”
9. Transport Canada – Safe Boating Guide (TP 511E) (2026-10-14): “Cross your arms tightly against your chest and draw your knees up close to them to help you keep your body heat.”
10. Transport Canada – Safe Boating Guide (TP 511E) (2026-10-14): “Huddle with others with your chests close together, arms around your mid to lower backs, and legs woven together. This also helps keep your group together until help arrives.”
11. US National Weather Service (NOAA) (2026-10-14): “If you cannot get to safety, assume the Heat Escape Lessening Position (H.E.L.P.) position. This protects the critical body areas and slows down the loss of heat.”
12. US National Weather Service (NOAA) (2026-10-14): “Keep as much of your body out of the water as possible.”
13. US National Weather Service (NOAA) (2026-10-14): “After escaping from cold water, get into a warm, dry, protected environment as quickly as possible. Even removed from cold water, a victim’s core temperature can continue to drop to dangerous levels.”
14. IMO – Guide for Cold Water Survival (MSC.1/Circ.1185/Rev.1) (2026-10-14): “Do not attempt to swim unless it is to reach a fellow survivor or a nearby shore, craft, or other floating object onto which you can hold or climb. Staying calm and still conserves heat.”
15. IMO – Guide for Cold Water Survival (MSC.1/Circ.1185/Rev.1) (2026-10-14): “Ideally, the survivor should be recovered in a horizontal or near-horizontal body position. Lifting a hypothermic person vertically can induce cardiac arrest.”
16. IMO – Guide for Cold Water Survival (MSC.1/Circ.1185/Rev.1) (2026-10-14): “It is important to remember that they will last only about three minutes and will then ease.”
17. NHS (2026-10-14): “remove any wet clothing, wrap them in a blanket, sleeping bag or dry towel, making sure their head is covered”
18. NHS (2026-10-14): “do not use a hot bath, hot water bottle or heat lamp to warm them up”
19. NHS (2026-10-14): “give them a warm non-alcoholic drink and some sugary food like chocolate if they're fully awake”
20. NHS (2026-10-14): “Hypothermia is a dangerous drop in body temperature below 35C (normal body temperature is around 37C). It's a medical emergency that needs to be treated in hospital.”
21. NHS (2026-10-14): “do not rub their arms, legs, feet or hands”
22. NSW Government (Transport for NSW) (2026-10-14): “If you're in the water with others, huddling is the best method of reducing the risk of hypothermia. Huddle close together to protect your chests and arms. This can reduce the rate at which your bodies lose heat and can increase survival time by up to 50%.”
23. NHS (2026-10-14): “do not give them alcohol to drink”
24. RNLI (2026-10-14): “It greatly increases your chances of making it through the initial shock.”
25. US National Weather Service (NOAA) (2026-10-14): “Always dress for water temperature, not for air temperature.”
26. RNLI (2026-10-14): “Anything below 15°C is defined as cold water and can seriously affect your breathing and movement, so the risk is significant most of the year.”
27. US National Weather Service (NOAA) (2026-10-14): “Carry an Emergency Position Indicating Radio Beacon (EPIRB), personal locator beacon (PLB) or VHF Radio.”
28. RNLI (Float to Live) (2026-10-14): “Practise floating in a supervised location like a swimming pool.”
29. Transport Canada – Safe Boating Guide (TP 511E) (2026-10-14): “The 1-10-1 Principle is a simple way to remember the stages of cold-water immersion and how long each one lasts.”
30. Transport Canada – Safe Boating Guide (TP 511E) (2026-10-14): “It can take an hour to go unconscious from hypothermia, even in ice water.”
31. US National Weather Service (NOAA) (2026-10-14): “Gasping for Breath & Rapid Breathing (occurs during the first 2-3 minutes or more)”
32. US National Weather Service (NOAA), citing the Red Cross (2026-10-14): “Hot water bottles and chemical hot packs may be used. Wrap the person in a towel or blanket before applying.”
33. US National Weather Service (NOAA) (2026-10-14): “Gasping for a breath or rapid breathing from sudden immersion can be triggered by water as warm as 77°F (25°C).”

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