By nature, swimsuits are among the simplest bits of clothing out there; if you retain your dignity at the beach and look good doing it, consider your mission accomplished. Because it toes the line between utility and fashion, swimwear has a hidden layer of complexity: A quality swimsuit should not only look great, it needs durable, stretchable and water-resilient fabric. For both men and women, most suits feature a blend of different fabrics – including natural and synthetic materials – and each brings distinct qualities to the table.


 

Tried-and-True Nylon

If you pick up a swimsuit off the rack, there's a pretty good chance it contains nylon. This lightweight manufactured fiber offers a lot of stretch and hearty moisture-wicking capability, making for speedy drying times. On the flip side, nylon swimwear may fray or fade after prolonged sun exposure.
 

Shapely in Spandex

Spandex lends itself to a great deal of modern swimwear, though it's typically not the sole fabric. As part of a material blend, soft and light spandex ups the swimsuit's stretchiness; the more spandex in the suit, the more shape-hugging it is. This makes it a vital component in competitive swimwear. Spandex slims the figure, but chlorine takes a toll on its elasticity over time.
 

The Poly Alternative

Polyester, not nearly as common in swimwear as its stretchier brethren, looks similar to nylon but is heavier and not very stretchable. Man-man polyester earns high marks for durability, but it's a thirsty fabric, which may weigh down your swim. Modern polybutylene terephthalate, or PBT, reduces absorbency, speeds up drying times and amps up the elasticity.
 

Classically Cotton

Early swimwear was made of wool or cotton, and the latter fabric can still help you nail the vintage look. While comfortable and retro-chic, cotton swimwear isn't quite as form-fitting as stretchier options, and it doesn't hold up well to chlorine. For a more durable, curve-hugging middle ground, seek a cotton blended with spandex or polyester.
 

High-Tech Trunks

Modern men's and women's swimwear sometimes packs a twist. Tan-through fabrics feature thousands of tiny holes that allow light penetration but look opaque when worn tight against the skin. On the opposite end of the spectrum, sun-protective fabrics, which cater specifically to fair-skinned folks, children and outdoor enthusiasts, disrupt ultraviolet rays. These materials are ranked by their ultraviolet protection factor on a scale of 15 to 50 or above.