Welcome to Mermaids Rock! The entrance to the mermaid realm in the deep, blue ocean... On a trip to the Red Sea, Kai and his friends explore an impressive shipwreck. Kai is intrigued by the human artefacts they find there but Coralie is worried about being discovered. Her fears become reality when a group of divers arrive. Will the friends be able to get back to Mermaids Rock without getting caught? The sixth book in an exciting series about the wonders of the ocean, perfect for fans of RAINBOW MAGIC, UNICORN ACADEMY and Holly Webb.