You can read this and other reviews at Things I Find While Shelving 
 [I received a free ARC of this book via NetGalley. This fact has no bearing on my review.] 
 When I get into a DNF streak, I start to get discourage and I wonder if I should have kept going, given the books I couldn't finish more of a chance. 
 But then I read something I absolutely love, and I know it was a good thing I didn't struggle through those other books, because then I might never have gotten to the ones I like. 
 That's how I feel about this book. 
 Threats of Sky and Sea is quite the adventure. Breena's life is turned upside down when the King's Adepts (Elementals) whisk her and her father away, claiming that the life she lived was not the one she was meant for - and that her father is not the man she has known him as for all her life. Breena is trapped in the world of false smiles and power hungry kings. She isn't sure who she can trust or what's going to happen to her or if she'll ever see her father again. 
 She makes some unlikely allies, and they work in secret against the King, who likes to have the rulers of neighboring countries killed so he can then swoop in and take over in the confusion. His sights are set on an Island nation now, but the nation has a strong navy, helped by their Water Elementals (Throwers), and Breena's country hasn't had a Thrower in sixteen years. So the king is finding weapons where he can, including marrying his son to the princess who was stolen from her home sixteen years before. 
 Ellison's world building is beautiful. From the different types of Adepts to the religion surrounding the Makers (OMG THE MYTHOLOGY!!) it was so well done and I really felt swept away into this world. Breena is a great character - she's strong, she's got her flaws (I think she's a little too trusting sometimes, but it works) and she knows when to fight and when to stay silent, which is something that happens frustratingly little in YA high fantasy, I've found... 
 There are great side characters, including Aleta (the stolen Princess), Caden (the Prince), Kat (the King's head Rider (air elemental)). Everyone is well developed, they didn't feel like caricatures or cardboard cutouts. 
 One thing I particularly liked was that Aleta and Breena did not get along to start, but Breena didn't chalk it up to Aleta being a bitch or anything petty like that, and they eventually came to be something like friends. 
 Over all, a very fun read. Looking forward to more in this world.