Surviving in cold water

Learn techniques to improve your chances of survival in cold water.

Your situation can change suddenly and without warning

Maritime NZ
Surviving the unthinkable

How to survive cold water immersion

1. Put on layers of clothing

If you need to enter the water, do not get undressed. A person wearing two layers of woollen clothing will lose less heat than a person wearing only a swimsuit.

If possible, wear as many layers of wool as possible and cover yourself with a waterproof layer. This will help trap warmer layers of water closer to the body.


2. Wear a lifejacket

A good lifejacket will help to keep the head and airway clear of the water, even when strength and mental capacity begin to wane. It will also make adopting heat-loss reducing postures easier.


3. Avoid alcohol

Safer boating and alcohol do not mix. Things can change quickly on the water. All on board need to stay alert and aware.

While alcohol may make you feel warm, it actually accelerates heat loss. It makes blood vessels dilate forcing blood closer to the skin.

About alcohol and boating

Survival techniques for water

Survive a man overboard

Maritime NZ
See the effects of going overboard

How to improve your chances of survival

1. Try not to panic

Panic can impair breathing and hasten the drowning process. Hyperventilation can occur when a person is unexpectedly immersed in the water. A mistimed breath can result in a laryngospasm, which sometimes results in loss of consciousness.

A person who does not panic may simply have to cope with hyperventilation, which will eventually subside.


2. Where possible, get out of the water

In water the body loses heat 20 to 30 times faster than it does in air.

Even if you feel colder out of the water, try to clamber on top of an overturned boat or any floating wreckage.


3. Think carefully before attempting to swim to shore

If you decide to swim for shore, consider that tests show an average person wearing a lifejacket and light clothing could swim about 1.85 kilometres in water of 10°C. In one Canadian case, a 20-year-old strong swimmer drowned within 5 minutes in 10°C waters.

When deciding to swim for it, consider:

  • your swimming ability
  • the weakening effects of the cold and anxiety
  • the huge overall heat loss that the swim will cause.

If in any doubt, stay with the boat.


Postures for conserving your heat and energy

Heat Escape Lessening Posture

a drawing of a person floating in water
  • Hold arms tight against the chest
  • Press thighs close together
  • Raise up the knees to protect the groin region


Children in cold water - should be sandwiched in the middle of the group, as they succumb to cold much more quickly than adults.

Huddle Posture

drawing of a group of people floating in water in a huddle
  • Press the sides of the chests and lower torsos together
  • Hug around the lifejackets
  • Intertwine legs as much as possible and talk to one another


How the body reacts to cold

The body must maintain the vital organs in its inner core – the heart, lungs, etc – at a constant temperature of about 37.6°C to enable them to function normally. At normal temperatures the heat generated by the body is carried by the blood to all regions of the body. The body automatically regulates its blood flow to control body temperature. Any excess heat is removed by transferring it to the outer layers for dissipation.

As the temperature of the environment falls, the outer layers of the body begin to cool. The body now reduces blood circulation to these outer regions, so that the cooling is not transferred to the important organs in the deeper regions of the body. Hands and feet feel cold because of the reduced blood supply to these areas. Shivering starts, as an involuntary muscular attempt to generate more body heat.

With further cooling, the inner core of the body now begins to cool.*

This is the beginning of hypothermia. The blood supply to the body’s outer regions is further reduced, as the body now takes drastic measures to maintain the temperature of its vital organs. Shivering may now decrease or stop. The organs in the core are now being affected. As the brain cools, there is reduced control and consciousness is affected. Further cooling of the core will cause the organs to stop functioning.

Consciousness is lost. Death will follow unless correct treatment is provided immediately.

* While progressive loss of body heat can result in loss of consciousness and death, many victims perish much sooner when immersed suddenly in cold water. Cold shock can affect some, causing cardiac failure within a few minutes. Increased breathing rates can lead to dizziness, and the muscles cool rapidly. Immersion in cold water can cause such rapid loss of muscular function that in minutes a person loses the strength to board a raft or even operate a flare.

A fit person in these circumstances quickly loses the ability to make even basic movements to help keep themselves afloat. There have been many recorded cases of drowning in less than 10 minutes – long before the body core temperature has started to drop or the person is affected by hypothermia.

Related information:

Getting a lifejacket

The right lifejacket will fit your activities and crew.

See all lifejackets

Types of beacons

Different beacons are designed for use in different environments.

Distress beacons