Echo has always been fascinated by human inventions, so she's especially interested when her class studies the history of the Titanic and the bacteria discovered there, Halomonas titanicae. When Mrs. Karp announces that the class will be going on an ocean trip to the sunken vessel, Echo is thrilled to have a chance to see it, since the ship is decaying and won't be around much longer.

The ocean trip isn't the only big news at school--a new merstudent, Anita, will be joining the class! But Echo and Anita immediately don't get along. Anita is rude to Echo the first time they meet, and all of Echo's friends seem to like Anita better than her.

As the trip approaches, the merfriends learn that the Titanic site isn't wheelchair accessible, meaning Anita won't be able to join the class. Her friends decide to boycott the trip, but Echo has been looking forward to it for weeks. Is Echo willing to look past her jealousy and give up the trip? Or can she find way for everyone to be included in both the ocean trip and her friend group?