I am in the beautiful island of Ventotene, whose first inhabitants were actually Greeks. They were colonists from nearby Pitecusa (modern Ischia) and ironically named the island "pandataria", provider of anything, because it has no water springs. They had to make do with rain water.
The nautical interest of this place, however, is from Roman times. Emperor Augusto decided to spend his ferie augustae here, so he built himself an imperial palace covering basically the whole island. He needed a port, so he had a port carved from a tuff headland! It is 200m long, large between 20 and 80m and 3m deep. You can clearly see its origin in the model here (the large white structure was a rain water tank).
The port, which is still in use, obviously had its storage rooms and depots, also carved into the tuff hill. These are shops and restaurants nowadays.
They even had bollards carved in the structures. They are also still in use!