Newest Stranger Things episodes finally explain what Upside Down actually is after nine years

Warning: This article contains spoilers for Stranger Things Season 5 Volume 2

Well, after five seasons over these past nine years, we have finally been told what the Upside Down actually is.

It’s obviously been a core part of Stranger Things since the show began but let’s be honest, plenty of us have just accepted it as this place without actually having a true understanding of it.

But in the recently released Volume 2, it was all laid out to us with a bit of explaining from Dustin (Gaten Matarazzo).

Eleven (Millie Bobby Brown) first called it the Upside Down back in season one, but it wasn’t until episode five of Netflix’s fifth and final season that Dr Brenner’s (Matthew Modine) journals revealed that it’s not just another world like they thought.

“We’ve slowly been peeling back the layers over the seasons, but in our final season, we wanted to explain finally what the Upside Down was,” the show’s co-creator, Ross Duffer told Netflix.

Dustin ended up being the voice for this as he initially told Steve: “It’s a wormhole,” explaining that it served as a ‘bridge between two points in time and space’.

A sphere - what they call 'exotic matter' - is at this point floating over Hawkins Lab and Netflix explain: "Vecna (Jamie Campbell Bower) didn't create the sphere — science did. It’s composed of exotic matter, a single source of energy, and it’s what’s keeping the highly unstable Upside Down together."

And when Nancy (Natalia Dyer) shoots it (Nancy's solution for everything these days), she sets off a sonic blast that's absorbed the flesh wall surrounding the Upside Down, leading to everything in its path being sucked into the void. While the shot 'very clearly disturbed' the sphere, it wasn't strong enough to destroy the wormhole.

This then leads to fans getting their first ever glimpse of what the Upside Down looks like from afar as the cameras ‘zoom out’.

Dustin is the one who cracks it. (Netflix)

“I think, ultimately, we really wanted it to have that hourglass shape, because we thought that was the simplest way to communicate such a big idea to the audience,” Ross told Deadline.

“But to do that, we had to zoom out. I can’t remember how many miles away visual effects figured out that we were by the end in order to see the full shape, but we had to go way out.”

Dustin draws a handy diagram to explain all this to the others (mirroring the same diagram the Duffer Brothers had used to explain the show). But the creators credit one of their writers with a lot of this, saying his ‘superpower’ is the ‘harder sci-fi aspects’.

Matt Duffer said: “As far as [when] it comes to this stuff, he’s smarter than Ross and I are, so he’s playing these things, and Ross and I are basically the Steve in the room going, ‘Huh?'”

So, the Upside Down is a wormhole and the Abyss is an alternate dimension. Get it? (Netflix)

“Illustrations help a lot. So we take a lot of those conversations that we have in the room and the way we help everybody understand it and map it onto the show.”

The illustration was essentially a cylinder with a circle at both ends, showing how the Upside Down connects Hawkins with another world the characters call the ‘Abyss’. This is where Eleven banished 001 too when she thought him in the rainbow room.

It’s said that this is the real home of the Mind Flayer, the vines, the Demogorgons – all those monsters we see - and it’s thought to be where Vecna has been going off to, not always the Upside Down.

It’s in that alternate dimension where Holly and the other kids have been kidnapped, entombed in the spires of the villain’s Pain Tree.

So, with the Upside Down finally cleared up, we’ve got to wait for the finale to see the gang off to try and stop Vecna from merging the Abyss with Earth.

Stranger Things Season 5 Volumes 1 and 2 are now streaming on Netflix. The finale lands at 1am on 1 January 2026.