Escape to the Moon Islands: Quest of the Sunfish (Book 1) by Mardi McConnochie
When Will and Annalie’s father disappears, they set out on a perilous sea voyage to find him. The motley crew of runaways put their faith in each other, and in a small sailing boat called the Sunfish.
In a world transformed by a catastrophic Flood, they embark on an adventure that will test their ingenuity – and their friendship – to the limits. The crew face off against storms and pirates, but the biggest threat of all comes from the Admiralty, the all-powerful navy that rules the oceans of the world.
The Admiralty are supposed to be the good guys, but the deeper the Sunfish voyages into the Moon Islands, the more they realise that nothing is what it seems.