It's a sleeveless top with a relaxed, slightly oversized fit. The chest patch pocket with decorative button detail and the curved hem give it more of a shaped, vest-style look compared to a standard tank top.
Cotton-linen blends wrinkle naturally, which is part of the fabric's texture. Most customers find a quick shake-out after washing is enough. For a smoother look, a light iron on low heat works well.
The fit is relaxed and slightly oversized, so choosing your usual size is recommended. If you're between sizes, sizing down gives a slightly more fitted look while still being comfortable.
Yes, the relaxed sleeveless silhouette works well over a swimsuit. The longer curved hem at the back provides good coverage.
The cotton-linen blend has enough weight to avoid being sheer. Lighter colors like white may have slight transparency depending on what you wear underneath, but the fabric is not notably thin.