Main Ventilation Shaft Section A is part of a network of ventilation shafts in the Frigate Orpheon in Metroid Prime that Samus travels through after the Parasite Queen battle in order to escape the frigate. This section contains a swarm of Parasites that are most easily avoided using Morph Ball. After the frigate crashed into the Tallon Overworld, a large portion of the room was flooded. In the unflooded portion, there is a swarm of Tallon Crabs. The flooded portion contains some Fish and a door leading to the Reactor Core.