Once you are in the city, it becomes increasingly clear Tripsea's purpose is much what you are using it for, a way port as ships travel. Often that trip is from one end of Icefia to the other, but other voyages are common as well. As mentioned, one of the three largest Icefian naval bases is here, to the west of the city as you near it. In addition, there are many dry docks, nearly as many as wet non naval docks.
Ancorage is a good example if you want to google a picture view of it. The city has just under 100,000 people.