The Lost Island of Tamarind by Nadia Aguiar
Puffin Books ISBN 9780141323862
Three children. Alone on the ocean waves, after a fierce storm throws their parents from the Pamela Jane into the icy waters below. Maya, Simon and Penny now face a wild rescue adventure that will lead them to a really magical place... Imagine an island with green mountains looming over pink sandy beaches and tide pools lit by the moon. An island with the darkest of secrets, where pirates lurk and jaguars roam - and a precious stone holds a power that is both wondrous and terrifying. This is where the children must go. No one from the Outside has escaped the island before. Danger is everywhere. But they can't turn back now. Could you?