Thanks It's meant to be unnatural. Done in the early style of TSR's D&D (1980's style) it was made for a small sandbox campaign.
What appears to be ocean to the east and north is not, it's a vast cliff with an "Ocean" of fog very much with the characteristics of Carbon Monoxide, poisonous and un-explorable with some rivers and waterfalls leading of it's edge.
Occasionally having a huge "wave" of heavy fog/gas roll over the edge onto land as a poisonous tsunami.
See here for my low fantasy map [link]