Cold-Water Immersion sports. In northern nations, swimming in cold water (also known as winter or ice swimming) has a long history. Up until a few years ago, only a small number of extreme athletes engaged in ice swimming. Ice swimming contests have been staged in ice-cold water (colder than 5 °C) for a while now.

Physiological Responses to Cold-Water Immersion. Cold water can kill  within seconds. Near drowning and hypothermia are two serious medical issues linked to immersion in cold water. The three phases of the body's reactions to immersion in cold water are:

1. Initial immersion and the start of cold shock;
2. Short-term immersion and performance loss
3. Long-term immersion and the onset of hypothermia. Specific survival risks for the victim of immersion are present in each phase and come from a range of pathophysiologic causes. All three stages of the immersion response have seen deaths.

Significant peripheral tissue cooling, particularly in the extremities, occurs for those who survive the cold shock reaction, with the majority of the effect occurring during the first 30 minutes of immersion. The neuromuscular activity is adversely affected directly by this cooling. Due to the poor blood circulation in the hands, which causes finger stiffness, poor coordination of the gross and fine motor activities, and loss of power, this effect is particularly noticeable in the hands.

As mentioned above, drowning occurs most frequently during the first two stages of cold-water immersion. True hypothermia, in general, typically only becomes a substantial factor in death if immersion lasts more than 30 minutes. The possibility of developing hypothermia exists for the person who survives the initial and brief phases of cold water immersion as a result of ongoing heat loss from the body, which progressively lowers core temperature.

A healthy body fluctuates at about 37° C. A body core temperature of 35°C or lower is the clinical definition of hypothermia, although the body becomes hypothermic whenever it is exposed to cold and its temperature falls below normal ranges.

Even hours after the rescue, a drop in blood pressure brought on by cold could lead the victim to lose consciousness or even stop breathing. Because of this, after being pulled from the water, a person with hypothermia has to get medical help as soon as possible.

Before attempting to swim to shore, keep in mind that you may start to lose your ability to swim in as little as a few minutes and that you will completely lose it in 30 minutes.

Acclimatization. For the future reference, in as few as five two-minute immersions in 59F-degree water, people can lessen their susceptibility to cold shock by 50%. (15C). Additionally, the majority of the habituation lasts for up to a year. The effect of a quick, cold shower is similar but not as strong.