The Tragedy of Tirath
The Sandimar Canal is the only channel of any appreciable size connecting the Sangen Sea to the outer oceans. It’s construction was begun by an enterprising dwarf clan, but eventually the dwarves had to partner with humans from the city of Sandimar to have any chance of completing the project. It took almost 100 years to finish digging and installing the lock system needed to deal with the changes in elevation. Before it’s construction larger vessels couldn’t penetrate the inland sea, and smaller vessels would be portaged across land in the north where the land separating them is much narrower.