I read this U.K. paperback about a decade ago, but I don't think it was a new release
Most of the Earth is flooded and the story takes place aboard loads of giant ships moored by the remains of the Scottish highlands.
The protagonist is an ex-marine, but his military service was like 50 mile swims and then knife fights in midnight lagoons
The dialogue is written in "hoots mon, it's a braw bricht nicht the noo" Scottish talking
The hero needs to find out who infected his girl with this stone disease, her and thousands of others are stored in sealed pods, each can only be released for burial once their DNA has been coded so they don't become a 'Typhoid Mary' for this disease. To do this the individual infection sources need to be included in the coding.
There are lines referring to the Great Floods and mass city drownings.
On-shore there are constant battles between survivalists and wild tribes; sometimes American tourists from the Rockies travel there with hunting rifles and get involved with the battles.
I think the body pods were named 'Kists'.