What's the Name of That Book??? discussion

There is a book I read last year, it is a dystopian teen and this is the most of the plot I can remember:
A girl lives on an island and the people warn that the sea will overtake the island, (in the future the sea levels have risen dramatically)
So, she leaves the island leaving behind her grandmother (not sure on this) to go & find the rumored "sky cities."
When they get there, there are large swaths of boats outside the wall; no one can get in.
She finds a way in when the gates open and she finds an island of people who sleep in trees.
Somehow, she gets into the city, I think.
She poses as one of them, & inside it is very techy and I believe the teens always have on skates.
Skip forward; she remembers being told that there is land trapped under the large icebergs.
With the meltings, she believes it has come to surface.
She steals this hugantic cruise ship boats to take all the sick/dying people outside the wall to the land.
While leaving, the boat nearly tips over as people try to get on.
That's all I sorta remember, does anyone know the title?

oh, and also, she has a device that lets her access a sort of virtual reality video game world; but no one uses it anymore.

could it be exodus?

Based on your description that sounds very much like Exodus

Key'Ahna, are you still looking for this or did you find it?

Thirding Exodus. It's gotta be.

Lobstergirl wrote: "Key'Ahna, are you still looking for this or did you find it?"

No response, moving to Abandoned.