|First appearance|| "X.A.N.A. Awakens, Part 2" (chronologically)|
"The Girl of the Dreams" (production-wise)
|Also known as||Sector 4|
|Terrain features||narrow paths, double-conical mountains, rare trees.|
The mountains of the Mountain Sector are shrouded in fog, there is more fog covering the Digital Sea. The sector is filled with moving pieces and narrow pathways. Due to this it can be hard to find Towers. In Season 1, the Mountains are a different color, being a dull and dark shade of purple. Normally when Towers are activated in this Sector, Bloks and Hornets guard them because they have the advantage in this Sector.
Appearances by the Scyphozoa and other monsters have happened as well. Sometimes, when the Lyoko Warriors jump off a platform, they are found in a different part of the sector. This sector was destroyed by Aelita by entering the Code X.A.N.A. in the way tower in Double Trouble, being the last of the first 4 sectors to survive.
Vegetation is very rare, in the form of sparsely populated pine trees.
- X.A.N.A. Awakens, Part 2 (debut)
- The Girl of the Dreams
- Laughing Fit
- Killer Music
- The Robots
- Zero Gravity Zone
- Rock Bottom?
- Ghost Channel
- Crash Course
- Dog Day Afternoon
- Kadic Bombshell
- Music to Soothe the Savage Beast
- Bad Connection
- Echoes (flashbacks)
Season Five: Evolution
Appearances in other Media
In Quest for Infinity, the Mountain Sector has numerous puzzles and platforms that must be navigated. Many of the passages and platforms are relatively small, and thus hard to navigate. Krabs are rare in the Mountain Sector due to the geography, but do occur. On the other hand, Hornets are extremely common. Bloks and Kankrelats are as common as they are in the show.
- The Mountain Sector is one of the 3 sectors to survive between Season 4 finale and unspecified rebirth of X.A.N.A. along with the Desert Sector and Sector 5.
- The Mountain Sector is the only Sector in Season 4 that never had a replika shown. It's possible that there was one, as when the Kolossus was first formed, it was shown that there were dozens of replikas.
- The Mountain Sector was the last Sector to be deleted by X.A.N.A.-Aelita using the Code X.A.N.A.. It was recreated between "William Returns" and "Double Take," reappearing in "Crash Course."
- The Mountain Sector got significantly brighter as the series went on from a drab grey colour, to a dark purple to an almost pink bright magenta.
- This was the first Sector to have a tower activated by Jeremie.
- This was the first and only Sector where Odd used Teleportation.
- This was the first Sector where Ulrich used the Overboard for the first time.
|Ice Sector | Desert Sector | Forest Sector | Mountain Sector | Carthage|
|Ice Replika | Desert Replika | Forest Replika | Mountain Replika | Volcano Replika | Carthage Replika|
|Other Virtual Worlds|
|Digital Sea | Cortex | Virtual Limbo | Simulation Bubble|
|Dormitory Building | Administrative Building | Cafeteria | Gym | Track | Park | Hermitage | Science Building | Playground | Garden Shed | Infirmary|
|Union Base | New Mexico Research Facility | Space Station | Jungle Research Facility|
|Renault Auto Factory|
|Factory Floor | Factory Lift | Lab | Scanner Room | Supercomputer Room | Assembly Room | Security Center|
|Kadic Academy | The Sewer | The Factory | Ishiyama residence | The Pool|