She-Ra: Princess of Power (1985)

S02E06 The Pearl

In "The Pearl," She-Ra and Mermista rescue a young horned whale from Hordak's clutches. After their daring escape, they bring the whale to Mermista's father's underwater realm, Salinius. However, unbeknownst to them, Hordak has secretly affixed a tracking device to the baby whale, allowing him to monitor their every move.