This book was also good. It takes place across the True Sea with Alina and Mal hiding from the Darkling and his forces. After an encounter with him, they sail wayward to the Bone Road for the second amplifier.
If you enjoyed this book or any in this series, I suggest either the Magnus Chase series or the Kane Chronicles, as both are similar when it comes to their descriptions of different creatures.

Shadow and Bone was a pretty good book in my opinion. It's about a girl named Alina Starkov becoming a Sun summoner and trying to get rid of the Fold, a dark and dangerous gash that cuts through the center of the country.
If you enjoy books with some fantasy magic elements and intense fight scenes, then you may enjoy the Kane Chronicles by Rick Riordan. It's centered around Egyptian mythology and is pretty funny in some parts.