It looks like something she might have purchased on her recent trip. I think it is a very nice look for a casual beach look. These two always look so good together, seems it is a great match.
NOW the only complaints about Maxima: Her hair looks like it needs major deep conditioning. I understand she likes the blonde (color) and also it is probably necessary to use heat tools on her hair and also tease/back comb it for more formal occasions. All that wrecks havoc on hair unless it is really, really very well taken care of, which doesn't seem to be the case. Also, in terms of makeup, Maxima seems to most often wear a more orange (bronzer) on her cheeks and then wears very (cool) pink lipstick ... it is NOT a good match. I really like her but she seems to need some good advice on her makeup and hair other than just for formal occasions.