According to Pausanias ("Description of Greece", 10.19.1.), prior to a critical naval battle with the Persians, Hydna and her father, Scyllis, volunteered to assist Greek forces by vandalizing the nearby Persian naval fleet. After reaching Greece, Persian king Xerxes I had moored his ships off the coast of Mount Pelion to wait out a storm prior to the Battle of Artemisium. Hydna was well known in Greece as a skilled swimmer, having been trained by her father, a professional swim instructor named Scyllias, from a young age. She was known for her ability to swim long distances and dive deep into the ocean.