Terry Pratchett’s Nation isn’t a Discworld novel. It might be better than a Discworld novel though. It’s about a boy in the South Pelagic (like the Pacific but different so the futzing around with history doesn’t get the geeks too annoyed) in the 17th(?) century. He’s an island boy on his way back from the island where he’s gone to do the rituals to get his man soul when a tidal wave sweeps through, killing everyone on his island and wrecking a ship well inland. Not everyone is dead though. There’s a British girl who’s the ship’s sole survivor.
I’d thought it was going to be a Robinson Crusoe type tale of these two kids surviving on the island but it’s about rebuilding a society after catastrophe. Other castaways and such keep on washing up on shore and the boy/man has to become a leader even though he doesn’t have a soul. He rages against the gods and finds the girl to be a rational scientific ally. It’s great. It’s funny, but not as silly as a Discworld book can be. Great stuff. For some reason our library has it in the YA section, but it doesn’t need to be.