Sector 1 / Biosphere (セクター1・バイオスフィア Sekutā 1 · Baiosufia ), is a lush jungle sector of the BOTTLE SHIP. During the ride from the Main Elevator, Samus Aran is notified that a level 3 alert is in effect in the sector. Samus is also advised not travel alone and to remain armed. It contains several jungle-inhabiting creatures Samus has seen before, but also several new ones.  The area also contains multiple Holographic Generators, the Breeding Room, the Scrap Block, the Bioweapon Research Center, the "rainforest", the Subterranean Control Room and the Biological Experiment Floor. The Diffusion Beam and Seeker Missiles are acquired here, and Samus activates her Space Jump and Screw Attack without consent.
Adam orders Lyle Smithsonian to secure a path to a facility, but he is later found dead with his corpse torn apart. Later, she finds a runaway Federation Soldier and follows him after she defeated a full grown Ridley. It is revealed that the runaway was James Pierce, seeing how his corpse ends up in the Bioweapon Research Center.
- Cyborg Zebesian
- FG II-Graham
- Fly Pod
- King Kihunter
- Little Birdie
- Mighty Griptian
- Mystery Creature
- Poison Gripper
- Super Kihunter
- Super Zebesian
Nintendo of Europe press release
"The Biosphere, for example, is a gigantic greenhouse containing a jungle complete with waterfall, rainfall and countless tropical – and aggressive – creatures and plants."
The Storms of the Biosphere
"The first sector I explored was called the Biosphere. The lush, tropical environments were homes to all kinds of jungle creatures, like Reos, Kihunter, and Wavers. All were aggressive, and often the only safe spots were the superstructures affixed to the trees. The synthesized precipitation did me no favors."
"As the Biosphere was the first simulated environment I saw, it took some time for me to discover that much of the area was completely holographic. Real features like rock walls and flowing waterfalls were surrounded by believable background vistas clearly designed for the benefit of the indigenous fauna."
"Sector 1 of the BOTTLE SHIP is known as the Biosphere. The lush, tropical environments are home to all kinds of jungle creatures, like Rios, Kihunters, and mobile flytraps. Almost all seem aggressive and hostile."
- The Biosphere is the only area where Adam does not authorize any of Samus's equipment. Instead, Samus self-authorizes her upgrades without his permission.
- Many areas of the Biosphere appear to have been damaged by overgrown plant life, despite the fact that the BOTTLE SHIP had only been abandoned for a brief time when Samus explored it (giving the plant life little time to grow to such an extent). It is possible that some areas of the station had been left unused by the researchers and thus retained damage from when the facility was originally decommissioned, or that the plant life there was capable of growing at abnormally fast rates.
- The sector is home to an infamous sequence in a dilapidated elevator shaft, where Samus is required to destroy the support structures for the elevator and jump into an alcove to avoid being crushed herself.
- A biosphere is also mentioned in Metroid Prime, in Tallon IV's Logbook entry (although it does not refer to an area, rather, a real biosphere, see below): "What remains of the biosphere is slowly fading due to exposure to Phazon radiation."
- Concept art depicts mechanisms identified as Stevenson screens in the Biosphere. However, no such devices are ever seen in the finished game. Despite this, both the Observation Room and the Swamp Zone, which contain Stevenson screens in the artwork, feature Holographic Generators that reveal an exit, and also observation windows (containing information terminals) that can be entered from the outside.
- The "intrigue" theme that plays after Samus leaves the Breeding Room is called "Sector 1 Biosphere", and is included in the Samus Archives Sound Selection.
In real-life, a biosphere is a closed, self-regulating system containing ecosystems, natural or artificial.