So with your mod Dana, is there a port/dock area in the city?
There are 4 boat stations around the island, but three of them won't become active until you actually reach the far end of the island and set them up. Then, the NPCs that act as boat travel will go to their stations. But, the first time you go to the other end of the island, you have to explore and walk there. Until you activate them to go to their stations, they're busy working or doing other things like farming or just milling about the city, and do not provide travel services until the far end of the island is explored.
There are a number of quests that lead up to being able to go to the city, so the first half of the quests for chapter one will be in khuul, solstheim, ald velothi, etc. You do not reach the new area by boat, silt strider, mages guild, or any other previously known method of transportation. I'll give a clue: Gamye, which was curiously absent from a certain Telvanni tower. Check your Lore.