(2) Sea Level
Overall, this book is super accessible to the 21st-century YA audience. The dialogue and settings are contemporary. People have cell phones and computers, and the characters speak like real teens do today. There is some dense-ish backstory with religious references and allusions to keep straight, and the prologue has a bit of antiquated vocab such as "fortnight" and "gelding," but that's all short-lived, so don't let it put you off. Plus, we're here to help.