Outdoor swimming how long should I stay in the water?

How long should I stay in the water when out open water swimming? There is no set answer, but there are things to consider (water temp, river or sea, time of day etc) and ways to think about this and apply the finding to you and your swim. So let’s get into it.

Water Temperature

If you measure the water temperature, then over time you will come to know which range of temperatures you are comfortable swimming in. Temperature gauges can be purchased cheaply and some high end watches come with them built in.

What affects water temperature?

Water depth

Water depth directly affects water temperature. If you are out for a swim in a shallow river and the sun is beaming down, chances are the water temperature of the river will be very pleasant. However, take the same scenario: a sunny day swim in the sea, lake or loch and just out from the edge the depth of water goes down to 400M then that water just beyond the edge is going to be cold. The sun will no longer have a direct effect. The top 2 meters of water in the summer in a loch can be 19c but underneath that water drops rapidly to 4c. For more information, check out https://staff.concord.org/~btinker/GL/web/water/water_temperatures.html

Time of day

This directly affects you and the air temperature more than the water, but it is all relative. If you’re going for an evening swim, beware of the sunset time, for as soon as the sun goes down, the temperature will start to drop.


What season is it? Obviously, the answer to open water swimming. How long should I stay in the water? Various from season to season, as well as several other factors. In general, we can stay in the water longer during the summer in comparison to our outdoor swimming sessions in the winter. There is also more chance of cold water shock, shivers and hypothermia in the winter.

Your Wild Swimming Kit

The kit you wear will affect how long you can stay in the water. It will help you acclimatise better and keep your core body temperature regulated. There is no doubt that if you’re kitted out in a full 5 mm wetsuit with neoprene socks and neoprene gloves, then you’re going to be comfortable in the cold water for a while. In fact, I have been deep in many a dark canyoning session for hours, warm to the core in my full kit. But if you’re out at the local beach in just your bathing suit, then it is more important to make sure you are aware of the other variables, to make sure you have a fun, and a safe swim.

River Catchment Area

Open-water swimmers love rivers, and if you are open water swimming in a river, then you need to be aware of the catchment area of that river. The catchment area is the surrounding area that feeds a river and that river will either feed into a loch, lake or the sea. The catchment area can have a drastic effect on the water temperature. For example on a beautiful, warm, spring day the river that hugs the base of a mountain in the highlands of Scotland, a mountain that is still covered in snow, is being filled by meltwater and will have cold water, no matter how beautiful and warm the day is, the water is going to cold. The main thing to look at here is the river being fed by mountains and snow melt. If so, the water will be cold and prepared appropriately.


When you are tired, you can feel the cold more intensely. Whether the temperature being perceived is real or not, being tired can affect how you experience it. Making immersion in not-so-cold water feel like you instantly want to get out of the water.

Swimming Experience

The last factor that will affect the temperature is your cold water experience. Your experience will allow you to best underrated the other variables and make the safe decisions when it comes to staying in the water or getting out of the water.

Advice for getting into the water

Ease yourself in, walk out and take it slow. Once you’re out deep enough, duck your head under. If the water is cold, your breathing will probably go funny.

Wait till your breathing is settled. Once your breathing returns to normal, swim a few meters and see how you feel. All going well, enjoy your swim.

Signs You Have Been In The Water Too Long?

Your hands and toes are usually the first parts of your body to tell you and listen to them.

Winter Swimming and swimming in cold water is not a competition

Swimming in cold water is not a competition. It is a way to enjoy the winter weather and get some exercise at the same time. There are many benefits to swimming in cold water, including exercise, improved circulation, increased metabolism, socialising and more. But at no point should you be competing to stay in the longest, you’re not Wim Hof and entering into hypothermia can be sudden and deadly. Remember, after the sim you need to get to shore and get warm, this takes time, so always leave the water with plenty of time and energy.

Swimming With Your Kit In A Dry Bag

A great way to ensure that you can exit at any time when you’re beginning to get cold is to swim with your kit and know your route/area.

First: Swimming with your kit, is fairly simple. A large tow float, like the Lomo swim run dry bag, will allow you to stuff your key essentials into the depths of its dry bag compartment. You could fill it with a changing robe, water shoes, food and your car keys. Then, if you start to get cold, you can exit at any safe spot and begin the process of getting warm.

Two: This is where knowing your route or swim area is key. Knowing where the exit points are, and for most, this will be fairly straightforward as most will simply make a route parallel to the river bank or the shore. Always know where you are. Check out our water safety guide for more. strengthen your extremities. It can also be a great way to prepare for a triathlon.

Cold-water swimming risks

Swimming in cold water can be risky, as it can lead to hypothermia or cold water shock. When a swimmer’s core body temperature drops, they may start to shiver, and their extremities may become cold. Wearing a wetsuit can help reduce the risk of hypothermia, but open-water swimmers should be aware of the dangers of swimming in cold water.

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