Polar Plunges and Cold-Water Dips: Safety First

A polar plunge or cold-water dip carries real risk, because sudden immersion causes cold shock: a big gasp, fast breathing, and a spike in heart rate and blood pressure. If you take part, choose an organized event with trained rescuers watching, go in gradually, keep your face out of the water, get out quickly, skip alcohol, and ask your doctor first if you have a heart condition or other health concern.

New Year's plunges, charity dips and cold plunging are popular, and many people do them without harm. This page doesn't tell you not to. It explains what happens in your body and how to lower the risk.

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Why plunges carry real risk

The National Weather Service (NWS) says that when your body hits cold water, cold shock can cause dramatic changes in breathing, heart rate and blood pressure (opens in a new tab):

• A huge gasp, then fast breathing. Cold water can trigger involuntary gasping, rapid breathing or hyperventilating (opens in a new tab). If your face is in the water when you gasp, you can breathe in water. The National Center for Cold Water Safety (NCCWS) also says to treat any water temperature below 70°F with caution (opens in a new tab).
• Heart strain. NWS says cold water can cause a sudden spike in heart rate and blood pressure, which can cause heart failure and stroke for vulnerable people (opens in a new tab).
• Panic. Cold shock can cause an immediate panic, fear or stress reaction that impairs clear thinking (opens in a new tab).
• Weak hands, fast. NCCWS says that in very cold water, it's possible to lose the use of your hands in under a minute (opens in a new tab). That matters when you need to grab a ladder or a rescuer's hand.

None of this depends on how fit you are. NCCWS says cold shock responses are intense and completely involuntary (opens in a new tab). Learn more in cold water shock and the 1-10-1 rule.

Choose an organized, guarded event

The safest plunge is one that someone else has planned for safety. When you choose an event, look for:

• Trained rescuers on site, in or at the edge of the water, with rescue equipment. CDC's general advice is to choose swimming sites that have lifeguards when possible (opens in a new tab).
• A marked, shallow entry area where you can walk in and walk out.
• A warm-up area nearby, such as a tent, a building or a bus.
• Clear rules about time in the water, and staff who enforce them.

We don't recommend or endorse any particular event. Ask the organizer how they handle safety before you sign up.

Never plunge alone. NCCWS's advice for anyone trying cold plunging is to be cautious and never go alone (opens in a new tab).

Get in slowly, and get out quickly

NCCWS gives specific advice for cold plunging, because sudden immersion in cold water causes an immediate and dramatic increase in blood pressure and workload for your heart (opens in a new tab):

• Enter gradually rather than plunging. (opens in a new tab) Walk in. Don't run and dive.
• Keep your face out of the water. (opens in a new tab) No dunking your head.
• Avoid breath-holding during immersion. (opens in a new tab)
• Keep it short. Get in, get out. Don't stay to swim.

After you get out, warm up right away. NWS advises that after leaving cold water, you get into a warm, dry, protected environment as quickly as possible (opens in a new tab). Have a towel, dry clothes, a hat and shoes ready before you go in. Watch your group for signs of hypothermia, which CDC lists as shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech and drowsiness (opens in a new tab). See hypothermia after cold water.

Skip the alcohol

Plunges are often parties. Keep the drinks for after. CDC advises you to avoid drinking alcohol before or during swimming, boating or other water activities (opens in a new tab), because alcohol impairs balance, coordination and judgment, and increases risk-taking (opens in a new tab). CDC also says do not give alcoholic drinks (opens in a new tab) to someone with hypothermia. More in alcohol and swimming.

Who should ask a doctor first

This is not medical advice. Ask your doctor before a plunge or a cold-plunge routine if you have:

• A heart condition or high blood pressure. CDC notes that heart conditions are associated with a higher risk of drowning (opens in a new tab), and NWS warns that cold shock can cause heart failure and stroke for vulnerable people (opens in a new tab). NCCWS advises getting a full cardiovascular checkup before you begin (opens in a new tab) cold water swimming.
• A seizure disorder. CDC advises one-on-one supervision around water (opens in a new tab) for people with seizure disorders such as epilepsy. See water safety with epilepsy or seizures.
• Any other health concern, or if you take medications that affect your heart, blood pressure or alertness.

Children cool faster than adults. NCCWS says children, with their smaller body size, cool faster than adults (opens in a new tab). If children take part, keep them within arm's reach, keep it very brief, and check the event's age rules.

Weak swimmers and non-swimmers should stay in water shallow enough to stand in, with a rescuer close by.

What you can do today

• If you're planning a plunge, ask the organizer how many rescuers will be there and where the warm-up area is.
• Book a checkup if you have a heart condition, high blood pressure or other health concern, and ask about cold water.
• Pack your after-plunge bag: towel, dry clothes, hat, socks and shoes.
• Agree with your group: walk in, face out of the water, short dip, no alcohol, nobody alone.
• Read how cold water shock works before the day.