When it comes to swimwear, most of us reach for whatever's on the rack — but the fabric you choose matters more than you'd think. Here's an honest comparison.
What is polyester swimwear?
Polyester has dominated swimwear for decades. It's cheap to produce, holds its shape well, and resists chlorine reasonably well. Most fast-fashion and mid-range swimwear brands use it as their default fabric.
The downsides? Polyester is a plastic. It sheds microplastics with every wash, doesn't breathe, and can feel clammy against skin — especially in and out of water. It also doesn't biodegrade, ever.
What is merino wool swimwear?
Merino wool swimwear is exactly what it sounds like — swimwear made from fine merino wool fibres, often blended for stretch and durability. It sounds counterintuitive (wool? in water?) but merino has been used in performance sportswear for years precisely because of how it handles moisture.
Merino fibres absorb and release moisture gradually, which means you don't get that cold, wet-fabric-clinging feeling. It regulates temperature naturally, dries faster than you'd expect, and is naturally odour-resistant.
The comparison
| Merino Wool | Polyester | |
|---|---|---|
| Breathability | ✅ Excellent | ❌ Poor |
| Temperature regulation | ✅ Natural | ❌ None |
| Odour resistance | ✅ Natural | ❌ Needs treatment |
| Microplastic shedding | ✅ None | ❌ Every wash |
| Biodegradable | ✅ Yes | ❌ No |
| Softness on skin | ✅ Very soft | ⚠️ Varies |
| Durability | ✅ Long-lasting with care | ✅ Long-lasting |
| Price | ⚠️ Premium | ✅ Budget-friendly |
So which is better?
For a quick dip at a resort pool, polyester does the job. But if you care about how your swimwear feels, how it performs across a full day in and out of water, and what happens to it after you're done with it — merino wins.
It's a premium choice, and it's priced accordingly. But it's also the kind of swimwear you buy once and keep for years, rather than replacing every season.
A note on care
Merino wool swimwear does need a little more attention than polyester — cold hand wash or gentle machine cycle, lay flat to dry. Treat it well and it'll last.