The Voyage of the Sable Keech (Spatterjay, Book 2)

Sable Keech is a walking dead man, and the only one to have been
resurrected by nanochanger. Did he succeed because he was infected by
the Spatterjay virus, or because he came late to resurrection in a tank
of seawater?
Tracing the man's last-known seaborne journey, Taylor Bloc wants to know
the truth. He also wants so much else - adulation, power, control - and
will go to any lengths to achieve them.
An ancient hive mind, almost incomprehensible to the human race, has
sent an agent to this uncertain world. Does it simply want to obtain the
poison 'sprine' that is crucial to immortality - and, if so, maybe
Janer must find it and stop it.
Meanwhile, still faced with the ennui of immortality, Erlin has her
solitude rudely interrupted by a very angry whelkus titanicus, and
begins the strangest of journeys.
Deep in the ocean the Spatterjay virus has wrought a terrible change
that will affect them all. Something dormant for ten years is breaking
free, and once again the aftershocks of an ancient war will focus on
this watery world. And Sniper, for ten years the Warden of Spatterjay,
finally takes delivery of his new drone shell. It's much better than his
old one: powerful engines, more lethal weapons, thicker armour. He's
going to need them.