Ahoy there me mateys!  I heard about this sci-fi book because it was a Booker Prize Nominee for Longlist (2019).  This novel is about what happens when climate change has raised the water levels of our planet.  It takes place on an island surrounded by the Wall which basically exists to keep all Others out.

Kavanagh is a young man who is about to serve his time on the Wall as a Defender.  All citizens have to do their two-year stint.  The consequence for letting someone over the Wall is to be thrown out on the other side to become an Other yerself.  I really enjoyed Kavanagh as a character.

The society at first seems rather benign.  All citizens have a chip and are guaranteed shelter, food, and clothing.  Ye also get a say into what yer job will be in the future.  Sure, ye might die on the Wall but once ye serve yer two years, it be fairly smooth sailing.  But reality of course is that there be a rather fierce class system where it be hard to work yer way up.  There are slaves even though they aren't called that.  No one wants to bring children into the world so one of the ways ye can work yer way up is by being a Breeder.  And above all there is always the fear of the Others getting in and taking precious resources and getting caught up in the consequences.

I thought the premise was excellent, the world-building was interesting, and I particularly liked the ending of this one.  Those who want solid answers might want to stay clear.  I keep reading these books about rising water levels because of where our planet seems to be headed.  I be interested in what authors can do to showcase the possibilities, as scary as they are.  Because remember the planet has been through this before.  Just look at Doggerland:

https://www.nationalgeographic.org/maps/doggerland/

Doggerland was an area of land, now submerged beneath the southern North Sea, that connected Britain to continental Europe. It was flooded by rising sea levels around 6500–6200 BC. Geological surveys have suggested that it stretched from Britain's east coast to the Netherlands and the western coasts of Germany and the peninsula of Jutland.  It was probably a rich habitat with human habitation in the Mesolithic period, although rising sea levels gradually reduced it to low-lying islands before its final submergence, possibly following a tsunami caused by the Storegga Slide.

This was an engrossing and quick read that I can recommend.  Arrrr!