Heatwaves and Hidden Dangers: Why Open Water Swimming Can Turn Deadly

When temperatures soar across the UK, it's natural to want to cool off. Every summer, thousands of people head to rivers, lakes, reservoirs, canals and the coast looking for relief from the heat. Unfortunately, these moments of fun can quickly turn into tragedy.

Despite the warm weather, open water in the UK remains dangerously cold throughout the year. Even during a heatwave, many inland waters remain below 16°C – cold enough to trigger cold water shock, a leading cause of drowning.

The Reality Behind the Statistics

The UK's National Water Safety Forum recorded 587 water-related fatalities in 2025, including 202 confirmed accidental drowning deaths. More than 57% of accidental drownings occurred in inland waters such as rivers, lakes, reservoirs, canals and quarries. Tragically, the final accidental drowning figure may rise as investigations continue. 

Young people are particularly at risk during warm weather. Data from recent years shows that people aged 10–29 account for over one quarter of accidental drowning deaths, with fatalities increasing dramatically on days when temperatures exceed 25°C. (RoSPA⁠)

Why Is Open Water So Dangerous?

Many people mistakenly believe that if the air temperature is 30°C, the water must also be warm. This couldn't be further from the truth.

Open water presents hazards that swimming pools simply don't have:

  • Cold water shock
  • Strong currents
  • Hidden debris beneath the surface
  • Sudden changes in depth
  • Underwater weeds and entanglement
  • Poor visibility
  • Slippery banks making it difficult to get out
  • No lifeguards or rescue equipment

Cold Water Shock

Cold water shock occurs when your body suddenly enters cold water. Your body's natural reaction includes:

  • An involuntary gasp for air
  • Rapid breathing
  • Increased heart rate and blood pressure
  • Panic
  • Loss of swimming ability

Even confident swimmers can drown within minutes because they cannot control their breathing or stay afloat. This is why many drowning victims are good swimmers.

Additional Risk Factors During Heatwaves

Heatwaves often encourage people to take greater risks.

Factors that increase danger include:

  • Swimming after drinking alcohol
  • Jumping from bridges or rocks
  • Swimming alone
  • Overestimating swimming ability
  • Entering unknown water
  • Trying to rescue someone without equipment

How to Stay Safe

If you're planning to cool off this summer:

  • Choose lifeguarded beaches or supervised swimming locations.
  • Never swim alone.
  • Avoid alcohol before entering the water.
  • Check local safety signs and warnings.
  • Enter the water slowly to allow your body to adjust.
  • Wear a buoyancy aid if taking part in paddle sports.
  • Tell someone where you're going.

What to do if you unexpectedly fall into cold water

Float to Live

  • Tilt your head back.
  • Keep your ears submerged.
  • Relax and control your breathing.
  • Spread your arms and legs.
  • Once your breathing has settled, call for help or swim to safety if possible.

What To Do If Someone Is Drowning

One of the biggest mistakes people make is entering the water to rescue someone. Many rescuers become victims themselves.

Instead, remember:

Call – Throw – Don't Go

  • Call 999 immediately.
  • Ask for the Coastguard if at the coast or ask for Fire and Rescue if inland.
  • Encourage the casualty to float on their back.

Throw something that floats:

  • Lifebuoy
  • Throw line
  • Rope
  • Empty cool box
  • Football
  • Any floating object

Never enter the water unless you are trained and equipped to perform a rescue.

First Aid for a Casualty Pulled From the Water

Once the casualty is safely out of the water:

If They Are Responsive

  • Reassure them.
  • Keep them warm using coats, blankets or dry clothing.
  • Monitor their breathing.
  • Seek medical advice, even if they appear well, as complications can develop after inhaling water.

If They Are Unresponsive but Breathing

  • Open the airway.
  • Place them in the recovery position.
  • Keep them warm.
  • Call 999.
  • Monitor their breathing continuously.

IF THEY ARE NOT BREATHING NORMALLY BEGIN CPR IMMEDIATELY

Current UK resuscitation guidance recommends:

  • Give 5 initial rescue breaths.
  • Then begin 30 chest compressions followed by 2 rescue breaths.
  • Continue until emergency services arrive or the casualty begins breathing normally.
  • Use a public access AED (defibrillator) as soon as one becomes available.

Rescue breaths are particularly important in drowning incidents because the primary problem is lack of oxygen.

Every Summer the Same Message Saves Lives

Every heatwave brings heartbreaking stories of families losing loved ones while simply trying to cool down.

The best way to prevent drowning is education. Understanding the dangers of cold water, respecting open water environments and knowing what to do in an emergency could save a life—perhaps even your own.

Before heading to the water this summer, ask yourself one simple question:

Would I feel confident helping someone if things went wrong?

If the answer is no, it's probably not the safest place to swim and you could benefit from undertaking first aid & CPR training. 

A 1 day Emergency First Aid at Work course will equip you with the skills to react confidently in an emergency, make a life saving choice today and book your course here:  https://www.bellsdowntraining.co.uk/first-aid/emergency-first-aid-work