Deeplight

Twenty Thousand Leagues Under the Sea meets Frankenstein in Deeplight, an inventive YA fantasy from award-winning author Frances Hardinge.
 
The gods are dead. Fifty years ago, they turned on one another and tore each other apart. Nobody knows why. Now, even coin-size scraps of dead god are worth a fortune because of the strange powers they’re said to possess. But few are brave enough to dive and search for them.
 
When 15-year-old Hark finds the still-beating heart of one of these deities, he’ll risk everything to keep it out of the hands of smugglers, scientists, and cults who would kill for its power. Because Hark needs the heart if he wants to save the life of his best friend, Jelt. But the power of a god was not meant for human hands.
 
With the heart, Jelt begins to eerily transform, and Hark will have to decide if he can stay loyal to his friend—or what he’s willing to sacrifice to save him.
 
“Glorious thematic complexity inhabits a wildly inventive world, with the menacing roils of a dangerous sea threatening the archipelago and touches of steampunk rounding out the fantastical elements.” —Bulletin of the Center for Children’s Books (Starred Review)