The Uchronic Black Sea is the body of water between Eastern Europe and Asia Minor. It is the route the group takes, by Meteora’s yacht, from Belgrade to Serpent Island in Uchronic Paris. The crossing is stormy and hostile.
It is the setting for the appearance of the lunar naga, who warns the group of a multi-naga ambush on the island.
Later, the Sea of Marmara, connected to the Black Sea, is the scene of the shipwreck of Meteora’s yacht.