How wetsuits keep you warm

Paddleboarder in full body wetsuit carrying Two Bare Feet inflatable paddleboard into open water

How wetsuits keep you warm

Retaining body heat in cold conditions avoids muscles seizing, your body going into shock and slowing of reflexes.

Wetsuits provide an effective way to maintain body temperature in and on the water, but how do they work?

Insulating your body

Neoprene wetsuits use water for insulation. A small amount of water enters the suit the first time you submerge. This is retained by the suit and warmed by body heat, creating a barrier between the cold water outside to prevent heat loss.

This insulating water layer fills well-fitting wetsuits, stopping more cold water from entering. Energy is conserved as your body doesn’t have to adjust suddenly to external changes in temperature.

If a wetsuit doesn’t fit properly, or is of low quality, it won’t be as effective. Water will end up being flushed in and out each time you submerge. This negates the insulating effect.

Infographic explaining how wetsuits work by forming an insulating barrier with water

Thicker wetsuits are warmer

Neoprene is a synthetic rubber material which is partly comprised of gas cells. This acts as an additional barrier. The thicker the neoprene, the bigger the barrier.

Wetsuit thickness is measured in millimetres, which is usually expressed in two or three measurements. The first number reflects material thickness on the torso; the second refers to thickness across the arms and legs. Sometimes arm thickness is stated separately, as a third value.

The thickness needed will depend on the activity. Some sports require more flexibility or range of movement, like SUP surfing or open-water swimming. In terms of design, this can mean thinner material around the limbs, while maintaining thicker material around the torso.

Seasonal differences

Wetsuit requirements change with the seasons. While a wetsuit may feel unnecessary in summer, it can provide protection from sun damage and prevent shock from cold water submersion in places where summer water temperatures remain relatively low.

Wetsuits usually range in thickness from 2.5mm for warm temperatures, up to 6mm for very cold water. People in regions with colder spring and autumn temperatures will benefit from a medium option, such as 4mm thickness.

Female paddler using rear back zip to fir into shorty wetsuit

Different cuts allow different levels of insulation

Shorty wetsuits have short legs and sleeves. They retain less heat than full wetsuits, so are suited to warmer waters or high intensity activities.

Some wetsuits come in two separate pieces – a top and bottoms. These can be full length or ‘shorty’ style, and are preferrable in situations where flexibility is more important than warmth. Separates allow more water to move in and out, which reduces insulation.

The warmest wetsuits are hooded. While movement is restricted, they insulate better as heat loss through the head is minimised. These are best used in cold water, for diving, or to stay warm out of the water when air temperatures are low.

Layering under a wetsuit

Rash vests protect against chafing under a wetsuit. This can be caused by trapped sand or salt rubbing against skin. They also offer another layer of insulation, which can be invaluable in cold waters.

In summer, non-thermal rash vests can be worn alone for a light level of insulation, and to protect against UV rays.

If a full-hooded wetsuit is not going to be needed much, a separate hood may be a better investment. A hood can also protect against surfer’s ear, which is caused by frequent exposure to cold winds and water.

Keeping your extremities warm when paddleboarding

For paddleboarders, wetsuit boots can be a useful addition for protecting the feet. While some prefer the tactile nature of decking against bare feet, it does mean the paddler’s feet may be in frequent contact with cold water.

Insulating wetsuit socks or boots can prevent numbness, mitigate against issues like chilblains, and help conserve energy. Socks can be slippery on paddleboards, but boots provide extra grip and protection from hazards.

In addition, a good pair of gloves can be indispensable on a cold day. They reduce the chance of numbness leading to loss of control over the board and paddle. Wetsuit gloves should be thick enough to keep your hands warm, but still allow full control of the paddle.

Close up of wetsuit boots

Avoiding flushing through stitching and zips

Gaps in zips and seams can allow water seepage, which reduces wetsuit effectiveness. Well-constructed wetsuits account for this by including pieces of material behind sturdy zips, called a zip baffle or ‘batwing’, and employing quality stitching.

The thickest neoprene won’t keep you warm if water flushes through the seams. There are different ways to stitch wetsuits, with different levels of durability, comfort, and watertightness.

Look out for wetsuits manufactured using blind stitching. This technique doesn’t penetrate the fabric externally, so there are no holes for water to easily flush through.


At Two Bare Feet all our wetsuits are constructed to the highest standards, with quality materials designed to keep you safe, warm, and comfortable on the water.

If you need help deciding on which type of wetsuit to buy, our friendly team is on hand to provide their expertise when dealing with your queries. As SUP, diving, and water sports enthusiasts, we’ve obtained a wealth of experience in the water – and have a lot of anecdotes to share!

In addition, our blog archive contains a variety of related resources, including our wetsuit temperature analysis and guidance on wetsuit tightness.

15 November 2021
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