There are girls under about 12 and girls over about 12. I believe that this girl was under. Of the people who wear bikinis, they are usually over 18 and there is probably a tendency for them to be at least over 13.
I walk at Greenlake many days with nicer weather and sometimes even in cloudy weather. I at times take photos of people being pretty, cute, beautiful, interesting, unusual or revealing. Most photos are of adults.