Do you know what a navy is? It's like a bunch of boats that people use to protect their country and travel across the water. The Byzantine navy was a navy from a long time ago in a place called Byzantium, which is now called Istanbul in Turkey.
The Byzantine navy was really important because the Byzantine Empire was surrounded by water on three sides. That means they needed to have a navy to help them protect their empire from enemies who might come by sea. The navy was made up of lots of different types of ships, like big ones called warships and smaller ones called galleys.
The Byzantine navy had many important jobs. They would protect the empire by guarding the sea routes, so bad guys couldn't get in. They would also make sure people who were trading goods could get in and out of the empire safely. Sometimes, the navy would even go to war against enemies who tried to invade Byzantine territory by sea.
The Byzantine navy had many skilled sailors who knew how to steer the ships and work together as a team. They also had special weapons on their ships like catapults, which were like a giant sling that could shoot rocks or other heavy things at enemy ships. The navy was really important for the Byzantine Empire to stay strong and safe.