Stick with recycled synthetics for swimsuits.

Yes, recycled nylon (often branded as ECONYL) and recycled polyester are the most sustainable choices for swimwear right now. They use waste—fishing nets, fabric scraps, plastic bottles—instead of virgin petroleum, and they actually hold up in water.

The problem with natural fabrics for swimsuits is practical: cotton, hemp, or Tencel absorb water like a towel. They sag, stretch out, and degrade fast in chlorine or salt. A swimsuit made from those will look sad after a handful of wears. Recycled synthetics keep their shape, resist UV and chemicals, and still let you avoid new plastic.

The catch is that they still shed microplastics when washed. Use a Guppyfriend bag or wash less often. And look for certifications (Global Recycled Standard, OEKO-TEX) to prove it’s not just marketing. Most major eco-swim brands (Patagonia, Summersalt, Vitamin A) use ECONYL