I found Dolamore's debut “Magic Under Glass” to be a charming and creative book that could have benefited from some tighter plotting and characterisation. It certainly sparked my interest for her next book, a standalone mermaid story, especially after Dolamore mentioned how she wrote the book to the scores of Studio Ghibli films (indeed, I noted in my earlier review how her creative worlds would be ideal for Hayao Miyizaki's next film.) While the mermaid craze never quite took off the way that many bloggers and publishers thought it would, there is still a gap in the market for a strong mermaid YA to join the myriad of vampires, werewolves, angels and other assorted creatures of mythology already so well known to readerrs. Unfortunately this book did not meet my excpectations.I found that many of the same problems I had with Dolamore's previous novel appeared in “Between the Sea and the Sky”. Wonderfully imaginative elements of world-building, including the mermaid-siren hierarchy, the relations between each of the species and the world of the winged creatures, the Fandarsee, were introduced to us but never fully developed. In “Magic Under Glass”, Dolamore introduced the strands of political and cultural complexities that I was desperate to know more about, yet such elements never came to fruition, and the exact same thing happens here. While there were moments of vivid descriptive scenes throughout her consistently strong prose, I never felt fully immersed in the world-building. To be honest, much of it felt very underdeveloped. I have a feeling this book may be marketed to a younger, more middle-grade audience. The prose and story-telling feels more suited to pre-teen readers, although it's very readable for all ages. I did find that the frequent dumping of exposition began to grate extremely quickly, especially since this is such a short book with very little action and a highly predictable plot.I did not find Esmerine to be as interesting or well developed as Nimira in “Magic Under Glass.” The idea of the young beautiful mermaid dissatisfied with her lot in life and yearning for more on the surface is nothing new. In fact, it's a staple of the great mermaid tales going back as far as Hans Christian Andersen, maybe even further. I can understand the harking back to influential tales but so little is developed from that point onwards that it can't help but feel stagnant and unsatisfying. This applies to pretty much every supporting character in the book, although nobody is ever really given any real time to shine or become more three-dimensional. Of course, this doesn't bode well for the romantic element, which felt too heavily reliant on the childhood friends trope to explain Esmerine and Alandare's relationship. One part of the book that really left me scratching my head was the depiction of humans. While mermaids and the Fandarsee are granted some variety of characterisation, pretty much every human is seen as selfish, rude or extremely ignorant of other species aside from themselves. They seem to view all others as a side-show novelty. I could understand this possibly for one or two characters from more isolated parts of the country, but these interactions and knowledge of other creatures are well known, so it didn't make much sense to have every human act like a fool when in the presence of a mermaid (whom they are especially susceptible to falling under their charms) or Fandarsee. While “Between the Sea and the Sky” possesses much of the charm and imagination of Dolamore's debut work, the same flaws are also still present and overwhelm the positive elements. Wonderfully creative elements and ideas are introduced but left to flounder instead of being given their deserved attention, while the characters and romantic element are pretty stock for the genre for the most part. The readability of its prose and short length make it ideally suited to younger readers, although the book itself is not without merit for readers of all ages. Once again, it's an ideal framework for a Ghibli film, but also hints are Dolamore's possible strengths as a short story writer. 2.5/5.