Odessa Sea - Clive Cussler, Dirk Cussler, Penguin

On a NUMA mission to the Black Sea to locate the wreck of a lost Ottoman Empire ship, Dirk Pitt and Al Giordino respond to an urgent Mayday from a nearby freighter. By the time they reach the area there's no one left alive - just dead bodies and the smell of sulphur in the air. As they investigate the fate of the lost ship, they're plunged deep into an extraordinary series of discoveries.