The answers are in the Down Deep. It might not be especially explicit, but it has always been implied, and with the Season 3 premiere, Silo is giving you all the clues you need. Ever since Juliette and George Wilkins first noticed a mysterious path mapped at the very bottom of Silo 18 on those old schematics, it has been at the back of our minds that the truth about everything has something to do with those tunnels.
You can definitely grab a few disparate pieces of lore at this point and pull them all into something resembling a few theories. The Algorithm is guarding something deep underground. Information about the tunnels has been historically erased and/or obscured. On the surface, there are nanobots to worry about. It’s clear that these things are all connected in some way, but for now, it remains elusive exactly how. There are, though, several ideas floating around the fandom, most pertaining to the nature of the tunnels.
It’s All Connected
The most prevailing theory is that the tunnels connect all of the Silos – or, at least, they once did. Even failing this, there’s an idea that all of the individual Silos might be isolated from one another but connected internally to a central hub, perhaps Silo 1.
In the Season 3 premiere, Ed Harwood, the Head of Mining, complains that the tunnels are a death trap since there have been 300 years of mining that the Pact forbids from extending too far beyond the Silo itself. Therefore, beneath the Silo is a warren of tunnels and shafts, all built on top of each other in a kind of cascade. Why would the Pact forbid the practice of digging outward if there wasn’t something to dig into?
Ed also suggests that the recent unrest and rebel sabotage have destabilised the mines further, which perhaps clues us in to what might have happened to the tunnels historically. If they were originally conceived to connect the Silos, and the Algorithm deduced that resource sharing and communication increased the risk of rebellion, it stands to reason that the existence of the tunnels would be obscured.
The Regime Is Fragile
On a thematic level, the tunnels and their outer limits represent the fragile stability of the Founders’ regime. As the geography of the Silo collapses physically, it also collapses politically, with the Algorithm having to go to extreme measures by using Camille to “program” Juliette as a token mayor to keep things under control.
The boundary of the tunnels is arbitrary and is therefore representative of the draconian nature of the Pact and the tyrannical rules that prohibit the Silo’s citizens from escaping their physical or psychological confinement. They’re literally boxed in, with the rules around digging ensuring that they never discover another Silo or anything else that might allow the light of day to creep into the prescribed worldview.
The claustrophobia and the rules designed to enforce it are the primary causes of civil unrest in the Silo. In seeing those barriers begin to collapse, it’s likely that even stronger rebellion will start to foment in Silo 18.
Memory Is the Key
It is not a coincidence that both Juliette in the present day and Charlotte Keene in the past are suffering from amnesia. A loss of memory is a loss of power, but it’s also a kind of soft reset so that things can be viewed through a new lens. And this is precisely what’s happening with Juliette in Season 3.
During the Council meeting, when Ed mentions the Pact forbidding digging too far outward, Juliette questions the logic behind the dogma. It’s one of the first times that anyone has done so, since people have been living in the Silo for so long, under the yoke of the Algorithm, that they have learned not to ask too many questions. Everything is just sort of blithely accepted. As soon as it isn’t, it begins to fall apart.
This also reflects how the Algorithm has used memory as a means of ultimate control. By erasing evidence that a thing ever existed and then allowing enough time to pass for that thing to fall into the category of myth, anything can be denied. When it comes to the tunnels, though, the diggers and doors and other lingering remnants prove what the Algorithm is so determined to deny.
