The Bio-Domes are 4 large housing units scattered around Apollo. They are artificial ecosystems used to support the Apollo Mining Colony. The Bio-Domes play a large role in the Easy Company Campaign and Path B of the Apollo Security Team Campaign. The Bio-Domes are a large source of infested, and they were sealed off in the events of the Apollo Security Team Campaign. Later on, Easy Company arrived and cleared the domes with the help of Dr. Bergmann, destroying Dome D in the process.
Found in the upper right portion of Apollo, it contains a massive horde of Zombies, Hulks, and Infested Marines. On higher difficulties Immortals will also spawn.
Found in the upper right portion of the Airlock, it contains a swarm of flying enemies, predominately Gargoyles. On higher difficulties Wraiths and Stranglers may spawn.
Found in the center of Apollo, it contains an armored horde containing Agrons, Stalkers, Banelings and a few Beastlings.
Found outside of the Laboratory, it contains a massive horde of Agrons,Gargoyles, and Stalkers. Notably on higher difficulties, Slashers will appear from this Bio-Dome.