The Geothermal Core is a room in the Magmoor Caverns. It appears in Metroid Prime. It has three pillars in a large pool of magma which requires power from a Spinner. By using the Spinner, the rotating lift platforms on the pillars rise and release access to a Bomb Slot. Activating this Bomb Slot will cause the pillars to raise the roof and a large and long Spider Ball Track will be revealed that lines the wall in a maze-like pattern. Samus has to roll across tracks, plates and tubes and sometimes even has to drop herself several meters in order to reach the next track. At the end of the track there is a door that leads to the Plasma Processing room, with Bendezium (in PAL and Japanese versions) blocking the door. Later in the game, both Puddle Spores will disappear from the room.
- South Core Tunnel (via Blue Door)
- North Core Tunnel (via Blue Door)
- Plasma Processing (via White Door)
- "Rotating lift platforms are in working order."
- "Collapsed Bendezium wall section is structurally unsound."
- It is possible to perform a Sequence Break to get to the top of the room and obtain the Plasma Beam before obtaining the Spider Ball.
- In the original NTSC version of the game, there is nothing blocking the Plasma Processing door. In the PAL version, Bendezium was added that blocks the door. In the Player's Choice version, the door is locked until Grapple Beam is collected.
- The Spider Ball Track is possibly the most difficult in the game. Because of the large distance, the enemies crawling on the wall and the deep falls Samus has to make, it is easy to fall down to the bottom of the room and have to start over again. Annoyingly, when Samus morphs on top of the Bendezium covering the door to Plasma Processing, she may roll off the platform and fall down.
- After activating the first spinner, the background music stops playing until the Bomb Slot is activated.
- Geothermal Core is the only room preventing 21% inbounds from being possible. Under 21% conditions, it is impossible to get Plasma Beam without either going OoB to get Floaty Jump or wallcrawling directly to Plasma Beam because of this room.
- Under 22% conditions, it is possible to scale this room inbounds using either Boost Ball or Space Jump Boots.