(Paperback)

While exploring a shipwreck in the Red Sea, Kai and his friends come face to face with humans for the first time. Can they get back home without revealing the secret existence of mermaids

(Paperback)

Accidentally transported to a dark, underground river, Marina and her friends discover an amazing jungle. But will they ever be able to get back home

(Paperback)

When Coralie finds a mysterious treasure map in a kelp forest, she and her friends cant wait to explore. But the forest has been destroyed. They'll have to do everything they can to save the forest creatures before its too late

(Paperback)

When Marinas dad goes missing in the Arctic while on a research trip, Kai and the friends help her on a rescue mission. But with the ice melting, the friends will need to find him fast...