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10 of the best sports swimsuits for cross training and triathlons
Whether you're heading to the sea or a lido, we've hand-picked our favourite swimsuits for sport
Tested by Ali BallE-Commerce Editor
Looking for a new sport swimsuit for your weekly cross training session at the lido? Or perhaps you're training for your first triathlon and are looking for a sport swimsuit to slip under your wetsuit – or even to wear al fresco for wild swims in the sea?
Whether you're buying a sport swimsuit for the first time, or your current cozzy is down to its last threads, we've got you covered.
What are the best sports swimsuits?
Here, we've hand-picked the best women's sports swimsuits on the market. Unlike the swimsuits you might wear to the beach, these are designed to keep you comfortable and supported as you rack up the lengths. Keep scrolling to read our full reviews.
What to look for in a sport swimsuit
Like the best sports bras or a pair of well-fitting running shorts, the best women's swimsuits won't move or slip as you power through the water. Here's what else you should be looking for when choosing the best sport swimsuit for you:
- Support: For larger-breasted swimmers, look for one-piece supportive swimming costumes that offer some sort of bust support in the form of padding or cups.
- UV protection: If you're planning on doing some of your training in your local lido or, if you're lucky enough, the sea, finding a sport swimsuit with UV protection is wise when it comes to protecting your skin from the sun's harmful rays.
- Fully lined: This simply means that every part of the swimsuit has an inner lining, which is designed to prevent the swimsuit from going see-through when wet.
- Chlorine-resistant: One of the reasons you might find yourself buying a new swimsuit every summer is that you're not investing in chlorine-resistant swimsuits. The chlorine in the pool damages the spandex found in most swimming costumes, causing them to not be as stretchy and the colours to yellow or fade. If you're planning on doing some proper swimming training, it's worth investing in a chlorine-resistant Lycra swimming costume, that will be better designed to cope with chlorine exposure.
- Design extras: Some of the swimsuits on this list will have racerback straps, allowing you to move freely whatever stroke you're focusing on, others will have a zipped front to make wiggling in and out of the swimsuit that little bit easier.
The best sport swimsuits for 2024
Ready to hit the pool? Here's our tried and tested edit of the ultimate sport swimsuits.
The much-loved HyperBoom Muscleback is one of Speedo's most popular women's swimsuits. It fits wells, offering good coverage across the chest, and the muscleback design offers plenty of flexibility, so you can really lay the hammer down during your freestyle intervals.
The Endurance + fabric is plush and stretchy, and the brand say it retains its shape and resists fading longer than any other swim material. It's 100% chlorine resistant and offers UV protection.
Another entry from Speedo. With its high neck and zip-up back design, the brand's Hydrasuit offers a flattering yet full coverage option, making it ideal for those with a larger bust (there’s even a bust shelf liner for added security).
There’s no security tab at the top of the zip (like you’d find on a wetsuit) but our tester hasn't had any issues with the zip coming undone during a pool session. In fact, they described it as their ‘perfect fit’, with a high cut leg allowing for total flexibility in the pool. The suit’s EnduraFlex fabric also offers higher chlorine resistance than standard swimwear fabrics.
Make sure you size up, though, as it does run small. Our tester is a UK size 10 but opted for a size 12 (34 in Speedo) and found this fitted best.
One of our testers has been using this Aleumdr swimsuit for the past two years and still claims it's the most supportive one piece they own for tackling lengths in the pool.
The round-neck design, cross-back and lightly padded cups make it a great option for those with larger breasts. And for less than £30, the fit is excellent, too — it doesn't ride up and maintains its shape and fit, even after multiple washes. Plus, there's plenty of patterns available.
If you're unsure which size to go for, we'd recommend going for the larger option. Our tester wears the M (UK 12-14) and it fits perfectly.
A firm favourite among competitive club swimmers, you'll need to get your measuring tape out or study the fit guide with this one, as it's part of Nike's performance swimwear range, designed for those who are taking their swimming training seriously.
The skinnier straps won't be supportive enough for larger-breasted swimmers but are tough and durable for those who can deal with a light amount of support.
Available in olive, black and bright red, this swimming costume from British-owned sustainable brand Davy J is one of our absolute favourites. Featuring a flattering square neckline, medium-to-high cut leg and cross-back straps, this cozzy feels super thick thanks to its double-lined fabric, which is made using 100% regenerated nylon yarn and provides serious compression and hold. We love it for open water swimming.
This is one of the best supported swimming costumes we've tried. It has built-in foam cups providing good breast support and also offers extra support around the middle; this not only aids comfort but gives a more flattering fit, so you feel confident in and out of the water. Available in a range of funky patterns and colours.
This seasuit from sustainability-focused brand Finisterre is made from recycled plastics, gives full-body coverage, offers SPF50+ protection and is designed to go in all water, from pool to sea. The loose cut is designed to avoid the suit being skintight, but it also means there is room under it for a wetsuit. There is a built in bra shelf and the geometric pattern is there to distort the contours of the body. Finisterre also do a matching Hijab.
As part of M&S's GoodMove collection, this supported swimming costume has been designed to feel flattering whether you're swimming lengths or chilling poolside. With padded cups, it gives you all the support you need to get through your session, and thanks to the brand's Secret Slimming technology, it holds your tummy in and shapes your waist for a flattering fit.
The zip-front makes getting the swimsuit on and off a little bit easier, plus the fabric is chlorine-resistant, meaning it should keep its shape and stretch.
If you're looking for a little extra coverage from your swimsuit, this Speedo legsuit ticks all the right boxes. There's also in-built bust support for comfort and a four-way stretch for ease of movement in the water. The legsuit is also fully chlorine-resistant and Speedo's Endurance+ fabric is designed to retain its shape and resist fading for longer.
This Roxy one-piece is perfect for swimming outdoors this summer. The long-sleeve design offers extra protection from the waves and the sun, while the swimsuit itself has UPF50+ protection. An easy back-zip closure makes it simple to get on and off, too.
It doesn't mention being chlorine-resistant, so this might be one you save for swimming in the sea.
How we test
All of the swimsuits in this guide have been extensively tested by the Runner's World editors and our wider team of wear testers. They've been worn in the pool, sea and lakes, during training for Olympic-distance and 70.3 triathlons. Any swimsuits that we deemed appropriate for lifestyle purposes only were discounted from our final round-up.
How to take care of your swimsuit
Like running kit, if you're going to invest in a good sport swimsuit, it's worth reading the washing tag to make sure you look after it properly.
Most swimsuits will need to be rinsed off under a cool tap as soon as you get out of the pool to remove the chemicals and chlorine from the pool. Of course, just soaking the swimsuit in cold water won't fully remove the chlorine from the fabric, so as soon as you get home, make sure you properly wash your swimming costume following the product's instructions.
Like your running kit, you'll also want to avoid exposing your swimsuit to high heat, so make sure you air dry your costume rather than putting it in the tumble dryer.
Ali is Runner’s World's e-commerce editor, specialising in testing and reviewing the latest running shoes, gear and tech. She has tested hundreds of products from the biggest running brands, including Nike, New Balance, On, Adidas and more. Ali speaks to some of the world’s top experts across footwear, running apparel, fitness equipment and nutrition to help runners make smart decisions when shopping online, from glucose monitors to help you nail your fuelling strategy to compression boots to aid your recovery. Ali has worked in health and fitness journalism since 2017. Before joining Runner’s World, she was health editor at Future Plc, working across brands including Coach, Fit&Well, T3, TechRadar and Live Science. A Boston qualifier, she’s completed nine marathons (including one set on a wild African savannah) and is on a mission to tick off every World Marathon Major. Her proudest achievement to date? Running a five-day 220km ultramarathon across Tanzania. Just don’t ask her to race a 10km…
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