This is a massive mithril and adamantite monstrosity that looms over the Ditch like a metal spiderweb fit for Lolth’s own throne. Erected by a now-defunct faction called the Forgesmiths before the time of the Great Upheaval, this suspension bridge defines the framework for the portal that has become known as the Seafarer’s Arch. So intricate and astounding is its craftsmanship and stark beauty that the Society of Sensation quickly dubbed it “one of the seven Wonders of the Multiverse,” alongside Thoth’s Library, the Modron Cathedral, and the Hollow World.
Records compiled by the Fraternity of Order for that time period are (much to the Guvner’s chagrin) sketchy at best, making it unclear to graybeards whether the bridge was built as a framework around the Seafarer’s Arch or if the portal was a munificent result of the bridge’s construction. All that can be said with any confidence is that the viaduct got its name because of the plane-spanning portal that lies below it.
“Sigil is a city of over one hundred square miles, and if any herd is barmy enough to believe that a burg of that size could possibly trade for all its needs by merchants trotting across the planes on foot, then I have got a bridge I can sell you for real cheap…” — A Knight of the Cross Trade, to a Clueless Prime
Also known as the Seafarer’s Portal or the Final Port-of-Call, the Seafarer’s Arch is a special type of planar gate, unlike all the others that dot Sigil’s architecture. According to the Rule-of-Threes, most portals fall within one of a trio of types —permanent, temporary, or shifting portals. However, the Seafarer’s Arch does not quite fit into any one of these divisions. It is always located under the Bridge That Spans Worlds, like a permanent portal. While it functions as a normal portal does, requiring some kind of impetus to act as a key to allow travellers to pass through, the Seafarer’s Arch has several different destinations at one time, like a shifting portal that simultaneously leads to multiple locations. Sailors need not wait a day or a week for the Seafarer’s Arch to shift its destination as with a shifting portal, as all the Arch’s destinations are accessible at all times. Lissandra the Gate-Seeker has dubbed this type of portal as a “Multiportal,” a label she has worked hard to have officially recognised by the Portal Registry in the Hall of Information.
A ship wishing to use the Seafarer’s Portal need not wait until its magical gate shifts to the proper destination. All it has to do is have the proper activation key for the port they have in mind. The specific gate key needs to be placed in a specially designed basket attached to the ship’s bowsprit, as it is the first portion of a vessel to pass through the confines of the portal. Maintenance of the spritcage and insertion of the gate key are duties usually imposed or bestowed (depending on the crew’s disposition) to the cabin boy. Spritcages vary in sophistication and design as widely as the bows of various ships. A Viking drakkar, for instance, might have its spritcage in the form of the gaping mouth of the ship’s carved dragon-bow; or a garbage scow may have little more than a tarnished box as its spritcage.
On Gate Keys
Any portal needs a gate key to activate its plane-spanning magic, and the Seafarer’s Arch is no different. While there are commonly known (or at least, relatively easily procured) gate keys to many prime worlds, items unique to these realms have also been known to function, such as a cinnabryl amulet to travel to the Savage Coast.
On the world of Toril, the Seafarer’s Arch leads to a large open sewer pipe that leads from the city’s Underdeep and empties into the Trackless Sea. The rapids below a moderately sized canyon in the Khalkist Mountains serves as the arrival point on Krynn. For Oerth, an oblong shoal of rocks in the Nyv Dyr serves as its portal. A waterfall in the kingdom of Cariele connects Sigil and Aebernys.
Other places that have known links to the Seafarer’s and Arch are Ortho (the Harmonium’s home plane), the Rock of Bral in Wildspace, to Io’s Blood Isles. Finally, while the portal works both ways, some destinations make it more difficult — carrying a scarab through Seafarer’s Arch will deposit a boat on the dry wastes of Amun-Thys, marooning it on the third layer of Arborea.
- In the Cage: A Guide to Sigil by Wolfgang Baur and Rick Swan, pg. 49.
- Polyhedron #137 article ‘Of Sigil and the Sea’; William James Cuffe, more info on that here.