Oliver and the Seawigs by Philip Reeve and Sarah McIntyre

Young Oliver Crisp's explorer parents have decided to settle down in one place. But within minutes of arriving at their new house on Deepwater Bay, his parents row off to investigate islands which are not on their map. And then, they don't return.

So begins a deep-water adventure for chapter-book readers featuring wandering islands, mermaids, a talking albatross, and sarcastic seaweed. Fearlessly, Oliver sets off to find (save?) his parents, and the boy who's seen everything discovers some really interesting new sights while he's at it.

I loved this highly illustrated juvenile fantasy. It's full of fun characters and a quick-moving plot that's just a little different than everything else.

Monstrous beauty

by Elizabeth Fama

Hester is a modern teenager who lives with the belief that for generations love and death have been bound together within her family.  Scientifically, there seems to be no proof, but she knows the safest choice is to avoid love.  Then she is drawn to Ezra who seems to have knowledge of her family's past.

Woven around Hester's story is one from another era.  This is the love story of a young man and the mermaid Syrenka.  Syrenka's kind are not understood by most humans.  The bond between the two appears destined for tragedy.

The reader begins the story quickly bonded to characters in both eras.  Fama does a wonderful job of giving the reader enough information to believe they have the story solved while holding a few important twists until the end.  
 

The audio version of this is a 2013 Odyssey Award Honor title, and for good reason.  Katherine Kellgren's narration is evocative.  She characterizes, and humanizes, multiple species and even the spirits of those long dead.