(EUC) Townsen tunic/caftan/dress XS

I don't really know what this is, but it's super cute. I've worn this as a bathing suit coverup and also thrown it on with denim shorts, tucking in the front. It's an oversized XS, so it could fit really up to a medium or large. No fabric tag but it feels silky, maybe like viscose? Very lightweight and cool. The navy and white stripes on the knit polyester neckline add an unexpected and youthful element and make it a little more casual and easy to wear.