It's a silk dress, I'm not in the habit of wearing them to the beach!
It's definitely appropriate, IMO.
But I would change the belt, and obviously no flip flops!
Weirdly, rarely, whatever, I don't think it suits the model. It looks nice in the photo, but when she starts moving in it, I had an "oh, oh no!" reaction! I went from like to dislike. I think that's down to the model though! She is not pulling it off.