A linen button-down is your best bet.

Yes, you can layer without looking like a marshmallow. The trick is fabric weight, not more clothes.

Stick with thin, breathable textiles: linen, lightweight merino, or a cotton voile. A loose linen shirt worn open over your swimsuit or bikini top adds warmth and style without bulk. Same idea with a thin cashmere or merino cardigan — not a chunky knit.

Avoid thick cottons, fleece, or anything with a hoodie lining. Those will puff you out. If you need more warmth, add a layer underneath: a simple tank or a long-sleeve rash guard. That keeps the bulk on the inside where it belongs.

A sarong or light wrap can also work, but only if it stays put. I’d rather have a shirt that buttons than a piece of fabric that needs constant adjusting.

Think of it as borrowing from resort wear, not camping gear. The goal is to add warmth without adding volume.