The Guardian review our Dulsie thermal swimsuit

A thermal swimsuit can improve your open water swimming comfort, providing warmth without restricting your swimming stroke.

When The Guardian’s Ella Foote set out to test the best thermal swimsuits for wild swimming, our Dulsie swimsuit made the cut – and for good reason. This long-sleeved swimming costume is designed for those cold dips where you don’t want the full faff of a wetsuit but still need that extra layer of protection.

Foote praised its no-nonsense design, generous fit, and ease of use. One of her biggest takeaways? The suit is perfect for swimmers with longer torsos, something often overlooked in standard swimwear. She also gave a nod to the strong back zip with a pull cord, meaning no awkward contortions required to get in and out.

Foote highlights that Dulsie comes with a three-year repair or replace guarantee (we call it the Alpine Bond), reinforcing its eco-conscious ethos. On which point Foote notes, it’s made from Econyl, a recycled material derived from ocean plastics and nylon waste, meaning it ticks both the sustainability and durability boxes.

This is a no-frills sort of suit, with a basic but effective design. – Ella Foote, The Guardian

But Did It Deserve to Be Left Out of the Top Picks?

You always want your products to be a top pick in any review, but Foote ultimately decided against ranking Dulsie among her best-in-test because the suit isn’t lined. Her argument? Once the sleeves got wet, the warmth benefit lessened. Fair enough – but our counter argument comes from what the Dulsie is actually meant for.

We never set out to make a thermal wetsuit alternative – this is a layered swim solution for those who want something more protective than a standard swimsuit but without the bulk of neoprene. It’s a compromise between flexibility and warmth, which is exactly what many wild swimmers are after.

And while it’s true that a full lining would provide more insulation, that would also mean less stretch and breathability, making it a tougher wear for longer swims. Besides, the lined front panel already provides core warmth where it’s needed most – a clever design choice to balance comfort and performance.

Final Verdict: Open water hero or villain?

We are delighted the Dulsie’s practicality, fit, and sustainability credentials have shone through, and for swimmers who struggle to find suits that cater to longer bodies, this is a great choice. Yes, if you’re looking for maximum thermal retention, you might need to look elsewhere (or layer up). But if you want a durable, sustainable, and easy-wearing swimsuit that keeps off the worst of the chill, Dulsie is one of the best out there.

Emily Foote is a highly experienced wild swimmer and the author of How to Wild Swim. Her review is well researched and comprehensive. Go check out her work. If you want to see how wild swimmers are using Dulsie you can read other reviews from the community or grab yours here.