At one time, the Romans avoided sea travel because the Italian peninsula had few good harbors. What evidence you can find to support the argument that this geographical drawback was eventually overcome?
The greatest evidence that his geographical drawback was eventually overcome is that the Romans became an incredibly powerful sea force, especially against Sparta.
The evidence that supports this is the way that they managed to conquer the Mediterranean completely and go as far away as Britain and various other remote places. They managed to conquer the North of Africa and control the seas all around Europe with nobody to bother them when they were at the peak of their power.
