SOLVED. Children's or YA Fantasy- a group of teens start living underwater. [s]

[Clark]

Premise: MC (girl) finds out her parents experimented on her (and others?) as a child, and as a result, she can breathe underwater and is overall more suited to living underwater. After an inciting incident (war?), she and a group of others flee to start living underwater.
Read: 2011-2016
Reading level: middle-school
Scene: I remember one scene where the group swims to close too shore and because of pollution they encounter this area where it's hard for them to breathe (in the water).

[Mai]

Maybe The Neptune Project by Polly Holyoke? From the reviews it seems to match your description and it was published in 2013.

[Clark]

Mai wrote: "Maybe The Neptune Project by Polly Holyoke? From the reviews it seems to match your description and it was published in 2013."

That's it! Solved! Thank you!