End of the world

Description
The term "end of the world" in this context does not refer to an apocalyptic event, but to a feature of terrain common in three-dimensional graphics. Terrain is commonly loaded in large rectangular sections, and developers typically extend the terrain beyond the normally reachable area within that block to prevent the edges of these blocks from even being visible, much less accessible.

Errors in terrain clipping can sometimes make these areas accessible, and they have an appearance roughly similar to the "end of the world" envisioned by many before it was generally accepted that the world was round. Instead of a waterfall or sheer cliff, however, players will see that the terrain they are walking on appears to be paper thin and can see the bottom of the "skybox", which may appear to be flat land, ocean, or simply a void. Walking along one of these often causes graphic anomalies to occur: characters, terrain, and other objects may disappear and reappear by turning or moving, and "afterimage" effects may appear over the edge as the camera turns. These anomalies are probably linked to malfunctions in the culling algorithms of the graphics engine, possibily because the character is located at the minimum or maximum possible coordinate along the terrain's X or Y-axis. In Guild Wars, it is possible to walk along these ends of the world, but characters cannot walk off these edges.

Reaching the Ends of the World
There are four currently known locations where an end of the world can be found through normal means:
 * The Great Northern Wall (mission): An end of the world can be found in the Charr camp when the chase sequence starts by running around the chasing Charr group into their camp.  Unfortunately, this part of the mission is timed.  Rarely, a moa bird spawns that can be killed and teleported to, but typically, getting to this end of the world requires initiating the chase sequence.
 * Cursed Lands: It is possible to walk through the northern portal from The Black Curtain into the Cursed Lands without triggering the normal transition by hugging the left wall.  An end of the world is found when entering the Cursed Lands in this way.
 * Talus Chute: There is a terrain clipping error in the southeastern area that allows characters to walk up the mountains at the side of the Talus Chute in a specific location.  This is found in the lower area with the icy sections along the eastern side.  Terrain clipping is unusual in these mountain areas, but it is possible to explore most of the eastern side of this terrain block.  The eastern end of the world is accessible in a couple locations in the northern and central parts of these mountains.  A vast ice sheet can be seen at the bottom of the skybox.
 * Eredon Terrace: This can accessed by normal means only if you are a member of the alliance that controls Eredon Terrace; there are alternative means of accessing this area, however.  There is a clipping error in the exclusive area that allows characters to walk across many of the mountains between Eredon Terrace.  The northern end of the world can be reached here.

Accessing Other Ends of the World
It is possible to access a surprising number of ends of the world by using skills that teleport or shadow step. Many of the area boundaries between explorable areas and between explorable areas and staging areas can be traversed with these skills without triggering the normal transition. When successful, the mobs, NPCs, and other characters are not loaded, but neither is any other terrain block. When a zone is small enough, its terrain may be included completely within the terrain block of the other zone, but typically, only a small portion of the zone, usually about the width represented by the compass, is included with the terrain block. In these cases, an end of the world is encountered by exploiting this trick.

Known ends of the world that can be accessed or viewed by shadow stepping or teleporting through portals are listed below (note that the following descriptions refer to shadow stepping since this is usually easier, but teleporting through these portals may also be possible):
 * Tyria (Prophecies locations)
 * Ascalon
 * Regent Valley (Post-Searing): Accessed by shadow stepping through the portal to this zone from Old Ascalon.  Oddly, some terrain is visible past the ends of the world in this area.
 * Eastern Frontier: Accessed by shadow stepping through the portal to this zone from Pockmark Flats.
 * Ruins of Surmia (location): Accessed by shadow stepping through the portal to this zone from Eastern Frontier.
 * Nolani Academy (location): Accessed by shadow stepping through the portal to this zone from Diessa Lowlands.
 * Diessa Lowlands: Accessed by shadow stepping through the portal to this zone from Ascalon Foothills.
 * Ascalon Foothills: Accessed by shadow stepping through the portal to this zone from Diessa Lowlands.
 * Northern Shiverpeaks
 * Traveler's Vale: Accessed by shadow stepping through the portal to this zone from Ascalon Foothills.
 * Deldrimor Bowl: Accessed by shadow stepping to yetis crossing into this zone from Griffon's Mouth.
 * Kryta
 * Scoundrel's Rise: Accessed by shadow stepping through the portal to this zone from North Kryta Province.
 * North Kryta Province and Watchtower Coast: Accessed by shadow stepping through the portal to Nebo Terrace from Cursed Lands.
 * D'Alessio Seaboard (location): Accessed by shadow stepping through the portal to this zone from North Kryta Province.
 * Divinity Coast (location): Accessed by shadow stepping through the portal to this zone from Watchtower Coast.
 * Nebo Terrace: Two be can accessed.
 * Accessed by shadow stepping through the portal to this zone from North Kryta Province.
 * Accessed by shadow stepping through the portal to Beetletun from Watchtower Coast.
 * The Black Curtain: Accessed by shadow stepping through the portal to Cursed Lands from Nebo Terrace.
 * Cursed Lands: Accessed by shadow stepping through either portal to Cursed Lands from The Black Curtain.
 * Tears of the Fallen: Accessed by shadow stepping through the portal to Tears of the Fallen from Stingray Strand.  (Note: this end of the world has an ocean around it, so the bottom of the skybox cannot be seen.)
 * Maguuma Jungle
 * Sage Lands: Accessed by shadow stepping through the portal to Sage Lands from Majesty's Rest.
 * Crystal Desert
 * Thirsty River (location): Accessed by shadow stepping through the portal to this zone from The Scar.
 * Southern Shiverpeaks
 * Spearhead Peak: Found by shadow stepping through the portal to The Granite Citadel from Frozen Forest.
 * Copperhammer Mines: Found by shadow stepping through the portal to The Granite Citadel from Tasca's Demise.  It cannot actually be reached, but it is visible.
 * Grenth's Footprint: Accessed by shadow stepping through the portal to The Granite Citadel from Tasca's Demise.
 * Ice Caves of Sorrow (location): Accessed by shadowing stepping through the portal to this zone from Talus Chute.
 * Cantha
 * Shing Jea Island
 * Sunqua Vale: Accessed by shadow stepping either through the portal to Shing Jea Monastery from Linnok Courtyard or to Linnok Courtyard from Saoshang Trail.
 * Kaineng City
 * Sunjiang District (explorable): Accessed by shadow stepping through the portal to Zin Ku Corridor from Tahnnakai Temple (explorable).
 * Sunjiang District (location): Accessed by shadow stepping through the portal to this zone from Sunjiang District (explorable).
 * Jade Sea
 * Mount Qinkai: Accessed by shadow stepping through the portal to Breaker Hollow from Archipelagos.
 * Eredon Terrace: Accessed by shadow stepping through the portal to this zone from Maishang Hills.  (Note: can be accessed by members of the alliance controlling Eredon Terrace simply by entering the exclusive area.)
 * Silent Surf: Accessed by shadow stepping through the portal to Leviathan Pits from Gyala Hatchery (explorable).
 * Elona
 * Istan
 * Cliffs of Dohjok: Accessed by shadow stepping through the portal to Champion's Dawn from Plains of Jarin.
 * Jokanur Diggings (location): Accessed by shadow stepping through the portal to this zone from Zehlon Reach.
 * Kourna
 * Marga Coast: Accessed by flagging a hero or henchmen on the other side of the portal to Sunspear Sanctuary from this zone and shadow stepping to the hero or henchmen.

More research is being done. See Portal Jumping Project for details.