World Model of Ultima VIII

The World Model of Ultima VIII at first sight seems confusing. With the world broken up into areas that are somehow connected with teleporters. That was, until Daniel D'Agostino from Dino's Ultima Page discovered more or less by accident, how the world in Pagan works. His original article can be read in the link at the bottom.

The Areas and Their Division
Ultima VIII basically distinguishes between two types of areas: meta-areas and sub-areas. The sub-areas are where the Avatar walks in, the meta-area contains all the sub-areas of a certain location.

To describe it better, the meta-area is just a big, empty void in which all the sub-areas of the location are located. The sub-areas are interconnected to each other with teleporters and special teleporters can lead to a different meta-area. For example, the three parts of Tenebrae are three sub-areas that are in the meta-area of Tenebrae. Leaving through the city gates teleports to a different meta-area (for example, Fishermen's Reef). The same goes for Argentrock Isle. The isle itself is one sub-area and the caves below the monastery another, yet they are in the same meta-area "Argentrock Isle" and connected to each other with a teleporter.

This is also the reason why the Theurgy spell "Divination" for example says "Argentrock Isle", even though the Avatar is in the caves below the monastery, as the spell only tells the player in which meta-area the Avatar is at the moment. Another example: the cave leading to the Plateau already is in the fitting meta-area, and therefore the spell says that the Avatar is on the Plateau.

The meta-areas themselves are totally closed off to each other and change to a different area is only possible via these special teleporters.

Going Beyond the Boundaries
Normally it should be impossible to leave the boundaries of a sub-area, therefore the player should never learn how the game is structured. However, the programmers didn't manage to eliminate all possibilities, missing four points where the Avatar can leave the sub-area, falling directly into the meta-area.
 * There is a place in the cave to the Plateau that allows leaving the boundary. It is hard to find. Go on the southernmost stepping stone until you see the south shore. From here, jump all the way to the edge of the southern shore. The cheat entrance lies in the southern rock jutting out to the water. Now, just walk straight into the wall, and turn a little west to get into it, but continue south. You should now be under the ground, and the Avatar will not show any more. Go south and a little west until the large stalagmite with brown mushrooms around it appears on the center of the screen, and go south. You will see the screen jerk slightly as when the Avatar jumps off a ledge. Now, you are free to run around the place.
 * Go to the temple where the Zealan gods are, and put two scrolls on the small table in the northwest corner of the room. Climb onto the scrolls on the table, and jump onto the wall. You are now over the wall between the Zealan gods' temple and Khumash Gor's tomb. Jump over, beyond the wall, and you've escaped the area's boundaries.
 * There is a broken wall in the Upper Catacombs, which allows leaving the boundaries.
 * In Herdsman's Valley it is possible to stack all the wood blocking the ghost cave and then use it to climb on the mountains. Walking further results in falling into the meta-area.

The effects are strange. Since the game has nothing it can draw, a strange Hall of Mirrors-effect sets in until the Avatar comes near another sub-area. It is impossible to leave the meta-area because of the invisible wall surrounding it, and also impossible to enter the other sub-areas, although it is possible to walk through the void in which Mythran's house floats. There are even some strange area remnants, such as in the Shrine of the Ancient Ones.

Leaving to return to the game is only possible with the Recall Item.