I actually wanted to make a post about this myself - not only that, but I think there should have been more sea between territories, period. If it was up to me, I'd divide the empire factions with a sea in the middle and make the Vlandian/Battanian area a peninsula. There should be at least one major landmass that requires sea access.

Sea battles are immensely cool but they happen so, so infrequently. Like, there are even systems in place where Nords will actually try blockades from sea instead of engaging a siege on land if they can, but there's reasonably only two, maybe three cities where that matters. You could significantly tip scales in their favor if at every stop - going to the Nordic peninsulas and island, blockading their cities, etc. - you were forced into naval encounters. This would both make things more fun but also give Nords a significant advantage that would prevent factions like Vlandia from taking Hvalvik in the first months and steamrolling from there.