1421: The Year China Discovered America by Gavin Menzies.
Back in 9th grade, I read TheSecretOfAtlantis and this book commits the same logical fail (circumstance inflated to reality). Although, this has more outright fail in it. E.g. Menzies describes a method of calculating longitude via lunar eclipse, which allowed Chinese navigators to make really good maps of where they went.
Which completely misses the point. In open water, you need to know your current longitude, and waiting 3 months for a lunar eclipse is not a functional answer. While you may have the best map in the world, without a way of calculating your current longitude on demand, it's practically useless.
Which you could also say about this book (well, you do practice reading critically, so it's not a complete loss ;).