Top Tips for Dealing With Hypothermia Risk in Open Water

Stay Safe, Warm, and Alert — A Lifesaving Guide for Swimmers, Triathletes, and Adventurers 

Open water swimming offers unparalleled freedom — gliding through lakes, rivers, and oceans with nothing but your stroke and the horizon. But with that freedom comes a silent, serious risk: hypothermia.

Unlike in a pool, open water temperatures can drop rapidly, and cold exposure doesn’t always feel dangerous at first. Yet hypothermia can set in quickly — even in water as “warm” as 60°F (15.5°C) — impairing judgment, coordination, and eventually, vital functions.

The good news? Hypothermia is preventable, detectable, and treatable — if you know what to look for and how to respond.

In this guide, we’ll cover the essential tips to assess risk, recognize early signs, prevent cold stress, and act fast if hypothermia strikes — so you can enjoy open water safely, season after season.

🌡️ Understanding Hypothermia in Open Water

Hypothermia occurs when your body loses heat faster than it can produce it, causing core temperature to drop below 95°F (35°C). In water, you lose heat 25x faster than in air — making open water a high-risk environment, even on sunny days.

📊 Water Temperature Risk Chart   

70–80°F (21–27°C)	Low	2–12+ hours
60–70°F (15–21°C)	Moderate	2–7 hours
50–60°F (10–15°C)	High	1–2 hours
<50°F (<10°C)	Extreme	<1 hour (as little as 15–30 min)

💡 Note: Wind, rain, fatigue, and body composition (less fat = faster heat loss) increase risk.  

🔍 Recognizing the Signs: Know the Stages

Hypothermia progresses in stages. Early detection saves lives. 

🟢 Mild Hypothermia (Core: 90–95°F / 32–35°C) 

• Intense shivering

• Numbness in fingers/toes

• Clumsiness, fumbling hands

• Slurred speech

• Confusion (“I’m fine!” when clearly not) 

✅ Action: Get out of water immediately. Warm up passively.  

🟠 Moderate Hypothermia (Core: 82–90°F / 28–32°C) 

• Shivering stops (danger sign!)

• Muscle stiffness

• Drowsiness, apathy

• Poor decision-making

• Loss of coordination 

✅ Action: Emergency response needed. Call for help. Begin gentle warming.  

🔴 Severe Hypothermia (Core: <82°F / <28°C) 

• Unconsciousness

• Weak or absent pulse

• Shallow or no breathing

• Appears lifeless 

✅ Action: Call emergency services. Begin CPR if trained. Do NOT assume person is dead — people have been revived after hours in cold water.  

🚨 “You’re not dead until you’re warm and dead.” — Medical adage  

🛡️ Top 7 Prevention Tips for Open Water Swimmers

1. Check Water Temperature — Don’t Guess 

• Use a waterproof thermometer or check local reports

• Rule of Thumb: If air temp + water temp < 100°F (38°C), consider a wetsuit 

2. Wear a Wetsuit When Needed 

• >65°F (18°C): Optional for acclimated swimmers

• 55–65°F (13–18°C): Recommended

• <55°F (13°C): Essential (full-sleeve, 3–5mm thickness)

• Add neoprene cap, booties, and gloves in cold water 

3. Acclimate Gradually 

• Never jump into cold water unprepared

• Start with 5–10 minute swims, slowly increasing time

• Cold water shock can cause gasping → water inhalation → drowning 

4. Never Swim Alone 

• Always use a bright safety buoy (increases visibility and provides flotation)

• Swim with a buddy or have a kayaker/spotter nearby

• Tell someone your route and expected return time 

5. Know Your Limits — And Respect Them 

• Fatigue accelerates heat loss

• If you feel unusually cold, weak, or confused — exit immediately  

• Don’t “push through” cold — it’s not toughness, it’s risk 

6. Warm Up Before and After 

• Pre-swim: Light jog, dynamic stretches — raise core temp

• Post-swim:

  • Dry off immediately

  • Put on warm, dry layers (hat, gloves, insulated jacket)

  • Sip warm (not hot) sweet drink (e.g., warm juice or broth)

  • Avoid alcohol — it dilates blood vessels and increases heat loss 

7. Use the “1-10-1 Principle” (Cold Water Survival) 

• 1 minute: Control breathing (cold shock causes gasping — focus on slow exhales)

• 10 minutes: Meaningful movement (swim to safety while muscles still work)

• 1 hour: Survival time (even if unable to swim, you can stay afloat and conscious for ~1 hour in cold water) 

🆘 What to Do If Someone Shows Signs of Hypothermia

✅ DO:

• Get them out of the water gently

• Remove wet clothing  

• Wrap in dry blankets, sleeping bag, or emergency foil blanket  

• Warm core first (chest, neck, head, groin) — not extremities

• Give warm, sweet drinks if conscious  

• Monitor breathing — be ready to perform CPR 

❌ DON’T:

• Rub or massage cold limbs (can force cold blood to heart)

• Give alcohol or caffeine

• Use direct heat (hot water, heating pads) — can burn numb skin

• Let them “sleep it off” — drowsiness is a red flag 

📞 Call emergency services immediately — even if the person seems to recover.  

🧠 Special Considerations

For Triathletes:

• Wetsuit rules vary by race — know the cutoff temps

• Practice open water swims in race-day conditions

• Have a post-swim warming plan (dry clothes in transition bag) 

For Winter Swimmers:

• Join a group with safety protocols

• Limit time based on temperature (e.g., 1 min per °F below 60°F)

• Always have a warm recovery space ready 

For Children & Seniors:

• Higher risk due to smaller body mass (kids) or reduced thermoregulation (seniors)

• Use wetsuits at higher temperatures

• Shorter swim durations 

💬 Final Words from Open Water Experts

“Respect the water. It doesn’t care how strong you are — only how prepared you are.”— Lynne Cox, Legendary Cold Water Swimmer  

“Your wetsuit isn’t weakness — it’s wisdom.”  

“The ocean rewards the humble and humbles the proud.”  

Final Thoughts

Open water swimming is a gift — but it demands respect. By understanding hypothermia, preparing properly, and listening to your body, you can safely enjoy the thrill of wild swimming for years to come.

So check the temp. Wear your gear. Swim with a buddy. And remember:

Adventure is out there — but safety is your responsibility.  

Stay warm. Stay alert. Stay safe.

Before You Dive In — Ask Yourself:

✅ Is the water temperature safe for my experience level?

✅ Do I have a wetsuit if needed?

✅ Is someone watching me?

✅ Do I know the signs of hypothermia?

✅ Do I have a warm plan for after?

The water will always be there. Come back to it — safely. 🌊💙