There should be a way to send ships up river, to allow for more accurate campaigns against the CSA. The Union sent steam ships up the Red River, a tributary of the Mississippi, to halt supplies moving in from Texas. We should have something like that, at least for some large rivers. Some examples could be the Mississippi, the Amazon, the Hudson, and the Congo Rivers. I'm sure there are other likely candidates. With such access, we should then be able to build naval bases on some provinces adjacent to rivers. Not all naval bases are situated on the coast.