The linked Danube, Sereth, and Bistritza waterways offer Dracula the closest concealed freight route from Galatz toward his castle.
After the paper trail ends in Galatz, Mina Harker studies maps without assuming ordinary motive. She concludes that Dracula's carriers must take the box up the Sereth and then the Bistritza, whose course approaches his Transylvanian home more closely than any other navigable route.
A fast double-crewed boat is already ahead. The hunters use the river as both Dracula's likely road and the axis for their divided pursuit by launch, horseback, rail, and carriage.
A cold winding river system running from the lower Danube through increasingly wild, steep, and wintry country toward the Carpathians.
The river route is Dracula's concealed path home and the geographic line that allows three hunter parties to converge on his cargo.