Between Sea
The Between Sea is the water system separating the eastern and western continents and surrounding the northern continent.
Currents
Cold arctic water is forced through narrow passages between landmasses, producing violent seas and difficult navigation. These conditions delayed rediscovery of the northern continent and limited long-distance naval development.
Navigation
For centuries, Uclean states built mainly coastal guard vessels. The far sea on the opposite side of the planet was believed infinite until the round globe became accepted.
Strategic role
Uarayania, northern ports and the river deltas became decisive once aviation and modern naval transport expanded in the 600s AFK.