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Best base layers for swimming in open water

Want to add some extra warmth to your outdoor swims? A swimming base layer could be the answer. Here, 220 Triathlon editor Helen Wester puts four to the test...


Looking to add some warmth to your open-water swims without investing in a thermal wetsuit? Well, we’ve got some good news. A swimming base layer will help you do exactly that.

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In fact, along with the best swimming gloves, neoprene socks and cold-water swim hats, a swimming base layer can help deliver a really comfortable open-water experience.

While many are designed to be worn under a wetsuit, they can also be worn on their own when you don’t need quite as much warmth.

But which are the best base layers for swimming? We test out a selection to find out…

Best base layers for swimming

Lomo Thermal Top

Credit: Steve Sayers
  • £29

Made of uncoated neoprene (so not shiny or grippy) this thermal top from budget-savvy brand Lomo is made from 1mm fabric, with flatlocked stitching meaning it’s both comfortable and flexible.

Designed for watersports, it can be worn alone as an extra warm layer or under a wetsuit. We tried it under our usual wetsuit which we wear for racing, and the extra layer under the very thin arms made a huge difference to how warm our arms felt; it also kept our body warmer.

The neck sat slightly higher than our wetsuit, too, stopping any trickles!

Verdict: Bargain for the money and adds under-wetsuit heat.
Score: 85%

Orca Heatseeker Vest

Credit: Steve Sayers
  • £54

Designed to be worn with or without a wetsuit on top for chillier surf or swim sessions, we found the flexibility and superb fit of the Orca Heatseeker to be a game-changer.

Easy to pull on over the head (though larger-busted swimmers may find it harder) our core was noticeably warmer when worn alone over a swimsuit or as an extra core warmth layer under our regular wetsuit.

Admittedly, it doesn’t keep your arms any warmer, which would be a benefit on longer swims (as explained in this issue’s article on p28), but it does have the benefit of not adding any restriction. orca.com

Verdict: A soft and comfortable way to add warmth to core.
Score: 85% 

Zone3 Neoprene Long Sleeve Top

Credit: Steve Sayers
  • £65

With so many cold-water accessories on the market, it’s worth just thinking a little about your own individual needs before splashing out – and this neoprene top is a case in point.

With long sleeves and made from 1.5mm coated Yamamoto neoprene, it ticks the boxes for warmth and hydrophobic properties. On this curvy female tester, we found that when worn over a swimsuit for added warmth it did the job, but rolled up around the waist.

It also did a superb job of adding warmth under a wetsuit, though putting both layers on together was a touch laborious!

Verdict: Warm with a handy rear zip; great under a wetsuit.
Score: 80%

Roxy Rise Springsuit

Credit: Steve Sayers
  • £105

Adding a splash of colour to this group test, this neoprene swimsuit from surf brand Roxy may seem an odd inclusion. It does have a place in this test, though, as for women looking to keep their body a little warmer on short swims, a neoprene swimsuit is a great option and much easier to get on and off on chilly days, plus it won’t rise up like a vest!

We tested the swimsuit version of the Rise, but it also comes with full-length legs (£135). The 1.5mm neoprene added warmth and definitely allowed us a longer swim than just a normal swimsuit. A bit skimpy on the bum, though!

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Verdict: Nice way to keep warmer on short swims and it fits well, too.
Score: 82%