Shadows of Acheron
The Ocean of Acheron is very dangerous indeed. Out to a perimeter of 20 miles offshore, sea travel and fishing are possible with little hindrance. However, any ships venturing beyond this 20 mile barrier would be in grave danger. Severe chaotic storms occur regularly and giant sea creatures lurk underneath the surface.
Generally, this doesn’t affect daily life much at all, as a 20 mile perimeter is plenty of room to work with for fishing and travel up and down the coasts. The only issue would be travel to and from the island nation of Arkadia, as it lies more than 40 miles off the northwestern coast of the main continent. In ancient times before The Cataclysm, large teleportation hub cities were maintained along the northwest coast that permitted travel to and from the island.