Warning: Spoilers for Stranger Things season 5, Volume 2!After nearly a decade, Stranger Things has finally explained what the Upside Down really is in the show. For so long, the Upside Down was thought to be some kind of parallel dimension. By Stranger Things season 5, Volume 2’s ending, it has now been revealed that the Upside Down’s existence is much more complicated and dangerous than we thought.

Stranger Things season 5, Volume 1, seemingly confirmed that the mysterious wall surrounded the Upside Down, with Hawkins Lab located at the center. Upon investigating how the lab connects to the wall, Dustin and the group make key discoveries that further explain what the Upside Down is, how it was created, and what it’s really used for.

Stranger Things Season 5 Reveals The Upside Down Is A Wormhole

Image via Netflix

While Dustin shares some insight into the Upside Down and how it connects to the exotic matter above Hawkins Lab, he breaks down everything for the Party in Stranger Things season 5’s “The Bridge.” It turns out that the Upside Down is actually a wormhole, serving as an “interdimensional bridge” connecting the real world and the world Vecna has been hiding in, which Dustin refers to as “the Abyss.”

At the center of the Upside Down is the exotic matter, and though it’s highly unstable, it essentially holds the bridge between worlds together. Vecna’s current plan in Stranger Things season 5 is to merge the two worlds by collapsing the bridge with the help of Holly and the kids. When Holly tries to escape from the Abyss, she falls through the sky of the Upside Down, but in reality, she’s falling through the wormhole.

The Upside Down’s Origins Involving Vecna & Eleven Explained

Although there had been many lingering mysteries regarding the alternate dimension throughout the series, Stranger Things season 4 revealed the Upside Down’s origins and how it was connected to Vecna and Eleven. Following the massacre at Hawkins Lab in 1979, Eleven used her powers on Henry, sending him to an entirely different world. We now know that his world was the Abyss, the home of the Mind Flayer and beings like Demogorgons.

That said, Stranger Things season 4 made it a point to show that the Upside Down was stuck in November 6, 1983. That was the day that Eleven was thought to have created the Upside Down after using her powers to telekinetically make contact with a Demogorgon. The truth goes much deeper than that with what’s revealed in season 5’s “The Bridge.”

Henry transformed into Vecna while he was stuck in the Abyss. Dr. Brenner was using Eleven to try to find Henry, and by making contact with the Demogorgon, her creation of the Upside Down was actually the creation of the bridge between their world and the Abyss. The Upside Down acted like a mirrored copy of the normal world, but it was only part of what connected Hawkins and the world Henry could claim as his new home.

How Vecna & The Mind Flayer Used The Upside Down To Target Hawkins

Just like how there are rifts between Hawkins and what was thought to be the Upside Down, there are breaches in the Abyss and the bridge. This allowed Vecna, the Mind Flayer, and creatures controlled by the hive mind to leave the Abyss, pass through the bridge, and enter through various rifts and gates into Hawkins or other locations in the real world.

It was never the Upside Down that housed Stranger Things‘ villains. Instead, the Upside Down just served as the location that all the show’s monsters had to travel through before getting to Hawkins. The Abyss was and still is where the Mind Flayer, the Demogorgons, and other creatures came from. It’s also where Henry officially became Vecna after being banished by Eleven in 1983.

Can The Upside Down Wormhole Be Destroyed?

Image via Netflix

The question heading into the Stranger Things series finale is whether the Party can destroy the wormhole, which would end the existence of Upside Down and the Abyss. By Stranger Things season 5, Volume 2’s ending, the group embarks on their final mission to take down Vecna and rescue the kids. Before coming home, they also plan to leave a bomb in the Upside Down.

In theory, if the dark matter is destroyed, the wormhole, or “interdimensional bridge” as Dustin also describes it, would collapse, destroying the Upside Down and the Abyss. As long as the gates and rifts between Hawkins and the Upside Down are sealed, it’s possible that Vecna’s rifts in the Abyss could lead to the world’s destruction if the bombing goes as planned.

Unfortunately, Kali thinks that she and Eleven should stay in the Upside Down when the wormhole gets destroyed. She worries that El’s existence will always lead to more people like Dr. Kay and Brenner looking to exploit her and Henry’s powers for nefarious means. If El does sacrifice herself with the destruction of the bridge, it would be a fitting end to the Upside Down since she inadvertently created it years prior.

How The Upside Down Connects To Dimension X

Before Stranger Things season 5 revealed critical information surrounding the Upside Down and its purpose, the franchise’s stage play, Stranger Things: The First Shadow, also uncovered key details about the dimension’s history. The play confirms that the Abyss is actually Dimension X, an alternate world that Henry first came in contact with as a kid, many years before he ended up there after being overpowered by Eleven in 1978.

In Stranger Things: The First Shadow, a young Henry encounters a Soviet spy who stole important equipment being used for a secret government experiment involving alternate dimensions and the Brenner family. The equipment, which is teased in the cave sequence during Stranger Things season 5’s “Escape from Camazotz,” ends up sending Henry to Dimension X.

It’s there that Henry first makes contact with the Mind Flayer, which ends up altering his life forever. Even though Henry gets back to his own world, encountering the Mind Flayer and Dimension X completely changes Henry’s behavior and personality, as seen in season 4. The event also leads to his psychokinetic abilities, causing the chain of events that involve Project Indigo, Eleven, and the creation of the Upside Down wormhole in Stranger Things.

Volumes 1 and 2 of Stranger Things season 5 are now available on Netflix. The series finale will be released on December 31, 2025!