Why Cold Water Catches Out Even Confident Swimmers

British sea temperatures are humbling. Around our coasts the water sits between roughly 6°C and 10°C through the winter and rarely climbs above 16°C even at the height of summer. That is cold enough to trigger cold water shock in anyone, however many lengths you can swim.

The response is involuntary and takes hold within seconds. You gasp, your breathing turns rapid and shallow, your heart rate surges, and your body's first instinct is to get your head clear of the water. If your face is submerged when that gasp arrives, you can inhale water before you have made a single conscious decision.

Most people who get into trouble in cold water do so in the first minute, not after half an hour. Fitness helps you swim; it does not stop the gasp reflex. Understanding that difference is the most useful thing you can learn before you walk into the sea.

Ease In, Breathe Out

Walk in slowly rather than jumping or diving. Splash water on your face, wrists and the back of your neck as you go, and let the gasp happen where you can still stand rather than in the thick of the waves.

• Wade to around waist depth and stop. Breathe out long and slow through pursed lips for a minute or two. The urge to pant will pass.
• Keep your breathing steady as you go deeper, and never hold your breath to fight the shock.
• Start swimming properly only once your breathing has settled. Do not head for the horizon the moment your feet leave the sand.
• Accept that a few minutes may be plenty, especially in winter. Ten minutes in single-figure water is a serious swim.

Heat escapes fastest from your neck, armpits and groin. A well-fitted wetsuit, a neoprene cap in winter, and boots and gloves for longer dips make a real difference to how long you can stay in comfortably.

Reading the Sea: Rips, Tides and Hidden Hazards

A rip current is a narrow, fast-moving channel of water heading out to sea, and it is behind a great many coastal rescues. Look for a gap in the breaking waves, a patch of water that appears darker and calmer than the surf around it, or a line of foam and debris being carried steadily offshore. That is where the water is running out.

If you find yourself in one:

• Do not swim against it. You will exhaust yourself long before you beat it.
• Swim parallel to the beach until you are clear of the channel, then head in on a diagonal.
• If you cannot make progress, float on your back, keep your airway clear, raise one arm and shout for help.

Tides deserve the same respect. Check a tide table before you leave the house, not when you reach the beach. Rising water can cut off coves, slipways and headlands within minutes, and spring tides move further and faster than most people expect. Waves are deceptive too — a modest half-metre shore break can knock an adult off their feet, and rocky platforms and groynes are far more slippery than they look from a distance.

Kit, Company and Planning Ahead

Almost every serious incident at the coast involves someone swimming alone, at an unpatrolled spot, with no means of calling for help.

• Take a tow float. It makes you visible to boats and board users, and gives you something to hold if you tire.
• Wear a bright swim hat and carry a whistle clipped to your costume or suit.
• Swim with someone. If you go alone, tell a person on shore exactly where you are going and when you expect to be back.
• Carry a phone in a waterproof pouch. Dialling 999 or 112 will get you the Coastguard.
• Choose a lifeguarded beach where you can, and swim between the red and yellow flags.

Booties earn their keep on pebble and shell beaches, and they protect your feet on rocky entries.

Warming Up Afterwards

Your body temperature keeps falling for a while after you leave the water, a phenomenon known as afterdrop. Get out of wet kit and into dry layers quickly, put on a hat, and get out of the wind. Warm up gradually with a hot drink and gentle movement rather than a scalding shower, which sends blood rushing to your skin and can drop your core temperature further.

Uncontrollable shivering, slurred speech, clumsiness and confusion are signs of hypothermia. Get help and call for assistance if it does not pass. And leave the alcohol until after the swim, never before it — it widens blood vessels and speeds heat loss just when you need warmth most.

If Something Goes Wrong

If you see someone in difficulty, do not enter the water yourself. Call 999 or 112 and ask for the Coastguard, keep the person in sight, and throw them anything that floats. Float to live is the advice for anyone struggling: lie on your back, spread your arms and legs, tilt your head back and fight the urge to swim hard. The cold will take your strength long before it takes your ability to stay afloat, and help is usually closer than it feels.