Dan Zander, Sea Patrol: The Hand in the Moon

His mom designed the first habitats for colonists on Mars and Europa; his dad ended a long war. But Dax Zander's days are full of surfing, hitching rides with whales and exploring the reefs around the family's undersea home pretty carefree. Until the morning three aliens arrive, pleading for humanity's help, as their distant ocean planet has just been attacked. While Earths leaders deliberate on a risky mission of mercy, Dax feels a call to leave childhood thrills behind and embrace a greater destiny: fighting for the survival of an entire civilization.