It's science fiction...isn't it?

Yes, it's sci fi, but it's not hard to believe that Dark Life by Kat Falls could really happen.  After the Rising (of the ocean, that is), a good chunk of our continent is under water.  Life on the Topside is getting pretty crowded, so some brave pioneers have formed an undersea territory, which is now their home.  Ty lives there with his family, and you soon learn he's a bit different from your average teenager - he's developed both a "shine" from eating so many bioluminescent fish and a special ability (I won't give it away) that some refer to as a Dark Gift.  He meets Gemma, a Topsider girl who's searching undersea for her brother, and soon they're on the run from the dangerous Seablite Gang, a group of outlaws led by the very scary Shade.  Action! Adventure!  And some very cool descriptions of the bizarre plants and animals that live in the deep.  I'm happy to see there's a sequel...Rip Tide.