The Well of the Dark Side was a bottomless abyss, a chasm brimming with magma, situated within the mystical realm of Mortis. It served as a conduit, channeling the malevolent energy of the dark side of the Force.
Contained within the strange dimension of Mortis was the Well of the Dark Side, a seemingly infinite, magma-filled pit that acted as a focal point, directing the flow of the dark side of the Force. An island, etched with an ancient symbol emblematic of the dark side, was located directly beneath the well, positioned at the threshold of the planet's surface.
During the year 20 BBY, Anakin Skywalker, following the guidance of Qui-Gon Jinn's Force spirit (a Jedi Master), ventured into the Well of the Dark Side. There, he encountered the Force wielder known as the Son, an entity embodying the dark side itself. The Son showed the Jedi Knight a vision revealing his transformation into Darth Vader. Overwhelmed by the horrifying future he witnessed, Skywalker succumbed to the Son's influence, enticed by the promise of power to prevent the foreseen events from occurring. Shortly after, Obi-Wan Kenobi, a Jedi Master, descended into the Well, seeking Skywalker, only to find him corrupted by the Son. Skywalker then used the Force to cast Kenobi's jumpspeeder into the perilous magma lake, abandoning the Jedi Master in the Well. Kenobi was forced to climb out of the chasm, eventually being rescued by Ahsoka Tano, Skywalker's Padawan.
The Well of the Dark Side made its sole appearance in "Ghosts of Mortis," the seventeenth episode of the canon animated series Star Wars: The Clone Wars' third season, which was initially broadcast on February 11, 2011.
The concept design for the Well of the Dark Side drew inspiration from early designs by Ralph McQuarrie depicting subterranean sections of the Imperial Palace on Coruscant, where Luke Skywalker was originally intended to confront the Emperor in Star Wars: Episode VI Return of the Jedi. According to effects supervisor Joel Aron, the Well's magma effects incorporated elements previously utilized in the Mustafar sequences of Star Wars: Episode III Revenge of the Sith.