Lalani of the Distant Sea by Erin Entrada Kelly
When Lalani Sarita's mother falls ill with an incurable disease, Lalani embarks on a dangerous journey across the sea . . . Life is hard on the island of Sanlagita. To the west looms a vengeful mountain, one that threatens to collapse and bury the village at any moment. To the north, a dangerous fog swallows sailors who dare to venture out, looking for a more hospitable land. The women live in fear of the deadly mender's disease, spread by the sharp needles they use to repair the men's fishing nets. When Lalani Sarita's mother pricks her finger and falls ill, she gives twelve-year-old Lalani an impossible task - leave Sanlagita and find the riches of the legendary Mount Isa, which towers on an island to the north. But generations of men and boys have died on the same quest. How can a timid young girl survive the epic tests of the archipelago?