Sector 6 is a dark area in which the circular light surrounding Samus is always on. It is comprised mostly of cavern-like areas, although several futuristic styled areas are accessible. Adam seems to have a mysterious forboding when sending Samus to this area; it is later revealed to be because of the Restricted Lab and secret Metroid breeding project hidden in the sector.
In Metroid Fusion, Samus comes here in order to obtain the Varia Suit so that she can withstand extreme temperatures, allowing her to go to Sector 5 (ARC). The second time she comes here is when she needs to defeat the B. O. X. the second time, after it becomes infected by the X.
- B.O.X. Security Robot (infected/second encounter)
- Blue X
- Fake Missile Tank
- Mega Core-X
- X Parasite
- When Fusion is played on a Nintendo DS (including enhanced versions) or an emulator on a computer, the background is almost as bright as the spotlight around Samus. This is because these systems use a much brighter screen than the GBA.
- There are strange inactive arm-like mechanisms in the background of the nocturnal areas, that have no effect on gameplay. A similar mechanism can be seen in the Spaceport in Metroid: Other M.
- The name of sector (NOC), apart of being short for "nocturnal", means "night" in polish language. It is unknown if this was intentional or not.
- Sector 6 was shown in most of the gameplay footage for Metroid Fusion in The Metroid Legacy, included in the Gamecube Preview DVD.
"This sector is used to research nocturnal creatures."
"Nocturnal creatures prosper in the dark environments perfectly recreated in Sector 6."