How Can Rome Be Mystery Babylon Without A Seaport?

The Bible does not indicate that Mystery Babylon must have a seaport. It states that shipmasters stand by and watch as Mystery Babylon is destroyed. Rome is right by the Tiber River and Rome is also about 15 miles from the Tyrrhenian Sea. There is actually a part of Rome called Ostia that is bordered by the Tyrrhenian Sea. So this prophecy still fits Rome.