Hyale was one of a band of sixty of the younger Okeanid Nymphs which formed the core retinue of the goddess Artemis. Their names suggest they were Nephelai (Cloud Nymphs). Since many of the younger Okeanides were cloud nymphs quite a few found themselves as attendants of Aretemis. This is because Artemis once approached her father and asked for followers (see below).
"‘And give me sixty daughters of Okeanos (Okeanines) for my choir--all nine years old, all maidens yet ungirdled; and give me for handmaidens twenty Nymphai of Amnisos (Amnisides) who shall tend well my buskins, and, when I shoot no more at lynx or stag, shall tend my swift hounds.’"