*This is a follow up to a previous article I wrote entitled “The Breath That Could Kill You”. That article focused exclusively on the first involuntary breaths taken when the body is exposed to cold water. This article focuses on the other responses to cold water shock.

Words by Gene Cahill.
Photos provided by Richie Dunn, Sandra Bickerdyke, and John Perdzock.

For most experienced kayakers today, a wetsuit or drysuit is an essential piece of gear that is worn more often than not, even at times, when it seems that it is not necessary. Harsh and fatal lessons learned over the years, and a growing body of knowledge on the study of cold water immersion, ensures that most kayakers are adequately prepared for paddling in cold water. Such detailed knowledge wasn’t always available and despite this, there are still exceptions and unfortunately, there are still accidents, very near misses and in some cases, fatalities due to cold water immersion.

In the Spring 1991 edition of Sea Kayaker magazine, Moulton Avery wrote an article entitled Cold Shock. It would forever change Seakayaking – for the better. Moulton’s article did not go down well initially. He was accused of scaremongering, misrepresenting facts and making Upturned kayakcold water kayaking out to be more dangerous than it really was. Most of the letters in response to this article were critical and negative. But what Moulton had dared to write had, in the words of Carl White of the Association of North Atlantic Kayakers, “literally poured ice water all over SKINs (Sea Kayaking INdustry) notions of how to deal with the cold water hazard.” Most of the criticism focused on the arguments that kayakers could avoid the need for wetsuits and drysuits by simply avoiding capsizing, as though people had a choice! Moulton credits Eric Soares, author of Confessions of a Wave Warrior with helping to turn the tide of opinion. Soares had read Moulton’s article and concluded that the article should be “taped to the forehead of every sea kayaker”. Soares’ growing reputation and influence within the sea kayaking community in North America made people take notice.

So what exactly is Cold Water Shock? Simply put, it is the body’s physiological response to immersion in cold water. It is extremely dangerous and has resulted in many fatalities. Many deaths have mistakenly been attributed to hypothermia when in fact it has been death due to cold water shock. It can take a person up to thirty minutes in cold water before they become hypothermic, but cold water shock occurs the second the body is immersed in cold water. Cold water shock becomes a significant danger at water temperatures of 55º Fahrenheit (12.7º Celsius) or less. In the UK and Ireland, the RNLI has warned that at averages of between 10-15º Celsius (50-59ºF), waters are officially cold. The US Coast Guard goes even further and considers water below 70ºF (21ºC) to be cold enough to warrant special precaution against hypothermia. The National Centre for Cold Water Safety also recommends treating water temperature below 70ºF with caution, although it is between 50-60ºF (10-15.5ºC) when cold shock reaches its peak.

When the human body comes into contact with cold water, a number of simultaneous physiological responses begin to occur. The first response involves loss of breathing control. The body’s first response is a series of involuntary gasps, which, if your mouth is under water when these gasps occur, will result in immediate drowning. The gasping is immediately Hat, goggles and nose clipsfollowed by hyperventilation. This increases breathing rate by four to five times the normal breathing rate, between 30-60 seconds after immersion. The hyperventilation will also result in a reduction in carbon dioxide in the bloodstream – a condition known as hypocapnia. This can result in reduced blood flow to the brain causing dizziness, confusion and even lack of consciousness. A person’s ability to hold their breath in cold water is also reduced by as much as 25-30%. This has implications for kayakers attempting a roll. Despite the hyperventilation, victims also experience a feeling of claustrophobia, of not being able to inhale enough air. This can last for a number of minutes and increases the likelihood of panic and disorganised behaviour in the water.

Coinciding with breathing difficulties is the instantaneous and massive increase in heart rate and blood pressure. The sudden exposure to cooling skin causes constriction of the blood vessels, which greatly increases the chances of heart attacks in more vulnerable individuals. If you are lucky enough to survive the cold water shock phase, your next threat will come from physical incapacitation. As the cold water cools your muscles, your body becomes progressively weaker, you become increasingly tired, your hands and feet become numb andCold Water gear your arms and legs begin to stop functioning. As well as greatly increasing the risk of drowning, your ability to self-rescue will be affected, as will your ability to help others who may be trying to help you. Swim failure is a common result and so is the ability to position your back to the waves.  After about thirty minutes in cold water, hypothermia will begin to set in. However, as Professor Mike Tipton, one of the authors of Essential Sea Survival, says “if you are lucky enough to survive long enough to die of hypothermia, you have done very well; most die in the first minute of immersion”. The National Centre for Cold Water Safety in Virginia, (set up by Moulton Avery) also highlights a fourth stage of cold water immersion – Circumrescue Collapse. This is when the victim collapses just before, during or after being rescued. It can cause unconsciousness or heart failure and although the cause is not yet properly understood, it is thought to be as a result of a sudden drop in blood pressure.

For kayakers, cold water also brings other hazards – cold water rushing into the nose can disturb and upset your body’s equilibrium, causing either a capsize or a failure to roll; cold water shooting into the ear canal and hitting the tempanic membrane can disturb your positioning and sense of balance underwater, making it more difficult to roll. Over time, if the ear canal is exposed to repeated and prolonged cold water, it can lead to a condition called exostosis, more commonly referred to as surfer’s ear. This is a narrowing of the ear canal due to a growth of the bone within the canal. Although not yet proven, it is theorised Fox_Riverthat repeated exposure to cold water causes this growth of the bone. Symptoms include constant pain, recurring infections and, in the most severe cases, a constant ringing in the ear. A dry/wet suit is not sufficient to reduce these risks. A neoprene hat/hood is vital as most heat loss occurs through the head and neck area. Neoprene or dry gloves work better with pogies because if you do end up bailing out, your hands need to be sufficiently warm/dry to enable you to re-enter and reattach your spray-deck, something that may not be possible if you have to remove your hands from pogies. Paddling with others and being competent in and confident with each other’s rescue capabilities will also minimise threats to your life if immersed in cold water. To minimise the long-term damage of cold water to the ear canal, it is worth investing in – and they are very inexpensive – a pair of ear plugs. Many people will also wear a nose plug when paddling cold water.

The severity of cold shock is dependent more on the amount of skin that is exposed to cold water rather than on the temperature of the water. According to Moulton Avery, 20 years ago it was widely thought that as water temperature fell, the severity of the shock increased. However it has been discovered that this is not the case and the actual cold shock responses are no greater at 35ºF (1.6ºC) than at 50ºF (10ºC).

So how do kayakers minimise the risks of cold water immersion? The National Centre for Cold Water Safety has drawn up a list of 5 Golden Rules of Cold Water Safety: (1) Always Geared Upwear your PFD; (2) Always dress for the water temperature (not the air temperature) and no exceptions! (3) Field-test your gear; (4) Swim-test your gear every time you go out; (5) Imagine the worst that could happen and plan for it. More detailed information on these rules are available on the Centre’s website Each rule is followed by a real life case-study. Interestingly, the Centre also recommends that Kayakers who don’t know how to brace should stay off of cold water altogether.

An excellent trip report from 2012 and case study of the hazards of dressing inappropriately on a warm winter’s day is available at

So the next time you stand on the shore, looking out onto the lake, river or sea, with a warm sun glowing on your face, a light breeze blowing and calm waters ahead, make sure you know the temperature of the water you are paddling in, think of the worst that can happen and plan your kayaking trip according to those. Paddle hard but paddle safe!


  5. Baglow, Dr. Dave, “Surfer’s Ear – An Inconvenient Truth, article available at
  6. Avery, Moulton, “Cold Shock”, Sea Kayaker Magazine, Spring 1991 issue.

My thanks to Moulton Avery and Catriona Miller at the National Centre for Cold Water safety for answering a few of my queries and for kindly sending me a scanned copy of Moulton’s 1991 Article Cold Shock.



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