WOW. This book was amazing. I read 20,000 Leagues beforehand to familiarize myself with the source material and found it frightfully dull and all the things I was interested in (Nemo's backstory, character development) muted in favor of things I cared not at all about (lists of fish...so many lists of fish). Everything I disliked about 20,000 Leagues was done exceptionally in Daughter of the Deep. The character depths, the action, the fleshing out of backstories, etc. The cast of characters were amazingly diverse and really well written. The story was almost impossible to put down. And I absolutely LOVED how it ended.