Approximately fifteen kilometers out from shore (varying up to a kilometer depending on the day and area), a vast sheet of thick fog appears seemingly out of nowhere like a sheer wall, and lingers permanently around the island, presenting a formidable barrier to exploration by sea. The fog stretches straight up, past the clouds - in fact, estimates reach close to 60 kilometers straight up, presenting similar barriers to air travel. Visibility is near zero within it.
The fog penetrates the water all the way down to the seabed, in defiance of whatever medium it is placed in. This indicates that it is not made of water vapor, and experiments have confirmed this, but what it is composed of is still as of yet a mystery.
The fog is magical, and has been confirmed as such by mages living upon the island. Much study has gone into it. The fog itself, aside from it's everpresence, seems to have little affect on that which enters it, although whether this is true or not is still a matter of some debate. The fog is visible from almost any point on the isle, far in the distance, out over the water.
Many expeditions have been sent into the fog in an attempt to locate what lies beyond it, most of these by ship. Of these, only two have returned - both after having accidentally turned around without locating anything. Every other expedition has never been heard from again, and their fates are unknown.
The two sorties that returned both reported that the further the fog went, the more disorienting things became. Various magnetic anomalies were detected, and at times they encountered storms where the horizon, water and fog all seemed to glow a faint red, and instruments became heavily unreliable. Though these anecdotes have been reviewed and grilled to death by scientific and magical experts, it's still unknown as to what caused this phenomena, and unfortunately neither expedition was equipped with recording equipment that was hardy enough to survive the magnetic anomalies unscathed. To this day, theories run rampant as to the cause of these phenomena.
There is one exception to the line of unsuccessful explorations, that being a small sub-orbital rocket launched by one member of the community. Zazzak's Rocket was a sub-orbital craft that managed to fly above the atmosphere, and thus, the fog, bringing back flurry video and images from it's onboard sensor packages of other, nearby islands, and information on the curvature of the planet.
While this raised a stir, being held up by many as proving the theory that the fog does not mark the "edge of the world", the poor quality of the images recovered were decried as inconclusive by many. Worse, the war has, until late in Year 85, been a barrier in getting the news of the mission to Arcford and the citizenry officially, leading claims of falsehood to be made.
Occasionally small, isolated pockets of "ground fog" have been known to show up on the island, cloaking roads or isolated areas in thick mist, usually no bigger than 200 square meters. These have occasionally, anecdotally, been known to perform strange effects, but each case of this happening has been unconfirmed or unable to be strictly linked to the fog in question. These events are rare and do not last long, but can be somewhat distressing, and it's often easy to lose track of where one is walking or going, often leading travelers astray.