Cruz Coronado and his fellow explorers are jolted from their normal routines at Explorer Academy's classroom at sea and thrust into survival mode as the adventure continues in the fifth book in the thrilling fiction series. On an island nation in the Indian Ocean, the explorers venture through a vast underwater world and take part in a friendly robotics competition. But the tides of good fortune change quickly. Suddenly, Team Cousteau jumps into action to rescue a faculty member from the brink of disaster. Meanwhile, the team follows Cruz's mother's clues to a magnificent tomb and centre of spirituality precariously perched on the side of a cliff. There, Cruz is confronted by a familiar foe who's determined to stop him from completing his most important mission of all: retrieving the final pieces of his mother's cipher. In this life-and-death showdown, Cruz witnesses the ultimate sacrifice and uncovers a hidden message that makes him question his own mortality. And don't forget to check out the other books in the series: • Explorer Academy: The Nebula Secret (1) • Explorer Academy: The Falcon’s Feather (2) • Explorer Academy: The Double Helix (3) • Explorer Academy: The Star Dunes (4) • Explorer Academy: The Dragon's Blood (6) • Explorer Academy Future Tech • Explorer Academy Field Journal • Explorer Academy Ultimate Activity Challenge • Explorer Academy Codebreaking Activity Adventure