BCBGeneration Navy Coverup / Swim Cover / etc with seagull / bird designs

Unsure exactly how to classify this piece, it’s a family member’s and I can ask them need be, but I think it’s a swim cover / robe / etc Front piece is like a cardigan/robe, in that it is naturally completely open, so I don’t think this is a dress, but there is a button on chest and a waist string belt, to wrap each side closed (like a robe)