Version 1

Karly is a nice girl who loves swimming and is in her school swimming team. One day, while at the beach, she meets a young mermaid by chance. The latter has forgotten her name, her origins... everything. Karly must help her to get back home, while also dealing with rehearsal for a swimming competition.

Version 2

The same, but Karly, instead of being part of a swimming team, is a surfer. She meets the mermaid after a surfing session.