Naerys was enjoying the warm day in the Water Gardens. As daughter of prince of Dorne she had a privilege of having lazy and rich life. In Water Gardens there was nice, cool in comparison with hot and dry climate around.
Naerys already had quite developed body. Young boys, commoners and nobles, have already started giving her attention and some even tried to court her. In Dorne people are less prude than in other parts of seven kingdoms, and Naerys could easily indulge in some "fun", yet she hasn't yet.
Naerys decided to visit her older brother Jaehaerys, the heir of their father prince Maron (Even though there were "stupid " rumours that Jaehaerys isn't son of prince Martell but of Daemon Blackfyre, black dragon bastard and rebel). Jaehaerys was lonely even in crowded Water Gardens, too prude and too bitter for other young dornish people.