Why the underwire bikini top is back in 2026

For most of the 2010s, the bralette-style bikini top was the default. Soft cups, no boning, a relaxed fit that suited the decade's preference for undone, casual dressing. The underwire did not disappear entirely, but it retreated to the back of the rack. In 2025 and into 2026, it has been coming forward again. And the reasons are more interesting than a simple trend reversal.

What changed in the construction ¶

The underwire bikini tops of the early 2000s had a reputation problem. The boning was often rigid, the lining thin, and the fit unforgiving if you were not exactly the size the pattern assumed. Saltwater accelerated the degradation of the wire casing, and after a season or two the wire would start to migrate through the fabric. A familiar and unpleasant experience for anyone who wore them regularly.

The new generation of underwire tops is built differently. Several brands working in Japan and in Italy have moved to a flexible resin boning that bends with the body rather than against it. The wire casing is now typically a double-layer bonded fabric rather than a single sewn channel, which significantly slows the rate of saltwater ingress. These are not dramatic innovations, but they are the kind of incremental improvements that make a garment actually wearable.

The bralette's limits ¶

The bralette top works well for a specific body type and a specific activity level. For lounging on a beach or sitting at a resort pool, the soft cup is comfortable and the aesthetic is clean. For swimming, surfing, or any activity that involves actual movement in water, the lack of structure becomes a practical problem. The bralette moves with the water rather than with the body, which is not always what you want.

This is not a new observation, but it has been made more loudly in the last two seasons by a generation of swimmers and surfers who grew up with the bralette as the only option and are now looking for something that performs better. The underwire's return is partly a fashion cycle and partly a response to a genuine functional gap.

What to look for when buying ¶

If you are considering an underwire bikini top for the first time in a while, the construction details worth checking are the wire casing material, the cup lining weight, and the closure type. A hook-and-eye back closure gives more adjustability than a fixed band, which matters more with an underwire than with a soft cup because the fit needs to be more precise.

Japanese brands tend to size their underwire tops more conservatively than European equivalents, so if you are buying across markets it is worth checking the size charts carefully rather than assuming your usual size will translate directly.

• Check the wire casing: bonded double-layer fabric lasts longer than a single sewn channel
• Flexible resin boning moves more naturally than traditional metal wire
• A hook-and-eye back closure allows for fit adjustment
• Cup lining weight affects both comfort and shape retention
• Rinse in fresh water after every sea swim to extend the life of the wire casing

The underwire is not a revolution. It is a correction. A return to a construction that was always useful, now built well enough to be worth wearing again. Whether it stays depends on whether the brands making it continue to invest in the construction details that make the difference.