What Is The Coldest Water You Can Swim In?


What someone perceives as cold might be slightly different from how another person perceives cold water. However, as a general rule of thumb, cold water can be measured in bands.

Different to indoor swimming pools, which tend to vary from 25 to 31 degrees Celsius, open water swimming is slightly different, and swimmers are exposed to a variety of different temperatures that can sometimes be unpredictable.

In the United Kingdom, swimmers can be exposed to a variety of fluctuating temperatures while swimming. Ordinary temperatures in inland waters can often reach as low as zero (freezing) and reach temperatures in the range of 20 degrees celsius during the warm months, especially during peak summer weather.

Temperature bands for open water swimming

To help you gain a better understanding of the different measurements of cold water temperatures, let’s break each of the coldest ratings of cold down below:

  • Baltic: This is the coldest water temperature rating and falls between 0-6 degrees. This range of cold water is considered too cold to swim in and can feel as though you have been submerged in ice.

When exposed to this level of cold water, your body and limbs will soon become weak, and your skin can begin to turn shades of purple, red and orange.

More often than not, these sorts of cold water conditions are used in controlled environments, such as during sports therapy for athletes.

  • Freezing: This is the second coldest water temperature rating and falls between 6-11 degrees.

Freezing water feels very similar to baltic, although it’s not as painful as baltic, and you’ll find that you can swim in freezing water for longer than baltic water.

However, it is still not recommended to swim in for long periods of time, even in a thermal wetsuit.

  • Fresh: This cold water range falls between 12 to 16 degrees and is considered to be the minimum temperature level to swim in safely. You will need to make sure that you wear a wetsuit, although it will still feel pretty chilly!

Read Next: What is the best wetsuit brand?

As a side note, it’s very important to be careful when deciding to swim in cold water and to always exercise caution.

If you aren’t wearing the proper swimming attire or swimming in water that is too cold. In that case, you will be at risk of hypothermia and cold water shock, which is something that occurs when the cardio-respiratory system is submerged in cold water.

This can be fatal, so be sure to check the temperature and try to avoid swimming in open waters during the winter months, as temperatures can often fluctuate throughout the currents.

Can you get sick from swimming in cold water?

Yes, it is possible to become sick from swimming in cold water. When you submerge yourself in cold water, a variety of physiological responses will naturally occur in your body.

These responses can be extremely dangerous and are known for being precursors to hypothermia, drowning and even heart attack.

For this reason, it’s essential to make sure that you do not swim in temperatures that drop into the freezing and baltic range. It could cause you to experience something known as cold water shock, which is a natural response from the body in an attempt to protect against the cold water. However, the results can often be quite the opposite.

An example that we’re sure you’ve already experienced is walking into a cold shower, or stepping into the pool for the first time on holiday.

As soon as your body is submerged into the water, you take a gasp for breath, which is then followed by quick breathing and sometimes even shivering.

Now, on a greater level, if you were to submerge yourself in freezing water, then you would experience this on a more intense level.

Your body would react in a similar way and cause you to hyperventilate, though, in this instance, your blood pressure would be much more likely to rise rapidly in an attempt to keep your blood warm.

If left any longer, other effects of being exposed to cold water could kick in, which could then lead to you becoming so weak that you would be unable to swim to safety, which is officially referred to as swim failure. Swimming in cold water could also lead to hypothermia.

What is a comfortable ocean water temperature to swim in?

Generally speaking, a water temperature of around 78 degrees Fahrenheit (which works out to about 25 degrees celsius) is the optimum temperature for swimming in the ocean.

However, in the United Kingdom, the overall average sea temperature in the summer months tends to reach a maximum of between 15-20 degrees celsius.

Many people would find this temperature range to be a little bit too cold, although it may be enjoyable on a hot summer day.

How long does it take for hypothermia to kill you?

The average body temperature is around 37 degrees celsius, and hypothermia is a seriously dangerous drop in body temperature below 35 degrees celsius.

If you swim in cold water for too long, you may be at risk of hypothermia, which can be fatal. It’s important to note that water conducts heat 25 times faster than air, which means the body’s heat loss is far quicker while submerged in water.

In the event that you were swimming or stranded in cold water, even though you would feel the effects of the cold water straight away, it would still take around 30 minutes for hypothermia to set in. However, it (on average) takes approximately 1 to 2 hours for hypothermia to kill you.

Before this occurs, though, your body would undergo a variety of reactions in an attempt to protect you. Which can cause things such as disorientation, muscle weakness, hyperventilating (or uncontrollable gasping) and other symptoms that may lead to you becoming unable to continue swimming.

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