The Wild Thornberrys (1998)

S1E8 Only Child

Eliza's vivid imagination spirals out of control when she becomes convinced that a teenage girl in town is, in fact, a dolphin intent on luring her sister, Debbie, into an underwater realm. As Eliza grapples with her fears, she embarks on a quest to save her sister from this fantastical threat, leading to a whirlwind of adventures and misunderstandings that blur the lines between reality and imagination.