Strong navy is really important because Rome was surrounded by water making them vulnerable to attacks from the sea. The Romans were protected by natural fortress *(such as mountain range) that protected them from potential attack from land. If they have a strong navy with them, their defense is almost impenetrable by their enemies in Europe.What was the Roman navy?
The Roman navy (Latin: Classis, lit. "fleet") comprised the naval forces of the Ancient Roman state. The navy was instrumental in the Roman conquest of the Mediterranean basin, but it never enjoyed the prestige of the Roman legions.