How did the empire's access to waterways help it to control the empire?

The Roman Empire first expanded around the Mediterranean and took over all the lands on its shores. This sea remained the heart of the empire. The Romans called it mare nostrum (our sea).

Italy was/is between the eastern and western basins of the Mediterranean. This strategic location made it easier for the Romans to gain control over the western part first, and then expand into the eastern part and to control both of these basins.