Nylon and polyester blends.

Nylon and polyester are the standard for quick-dry swimwear. That’s it. If the tag says “100% cotton” or “cotton blend,” put it back.

Spandex (Lycra/elastane) is added for stretch, but the base fabric is what matters. Nylon dries faster than polyester and feels softer, but polyester holds up better against chlorine and UV. Pick whichever suits your pool vs. beach ratio.

Avoid cotton like the plague — it stays wet forever and gets heavy. That “rash guard” material is just polyester or nylon with spandex, works great.