Pressure Plant was a location on the North-East Side of the Athena Map. It was added upon the release of Season 9 in place of the Volcano which was destroyed during its eruption. During Season 9 it was converted into a factory to construct the Mecha, which became the basis of The Final Showdown. It is possible that Steamy Stacks located on the Apollo map from Chapter 2 is a spiritual successor to Pressure Plant.
When it was first added the location was just a few reasearch buildings built on the hardened lava left over from the eruption, throughout Season 9 it was slowly built up to the rim of the volcano with solid concrete structures forming the grounds on multiple layers. During Season X the concrete remained but the buildings were removed and replaced with the robot factory. As the weeks went on the centre section's floor moved lower and lower with the Mecha's body parts appearing from the legs up. Players could use air vents in the pit to fly around the robot.
After The Final Showdown event the floor of the pit remained lower and the location stopped updating. Pressure Plant remained unchanged during Season X and was ultimately sucked into the black hole during The End event along with the rest of the Athena map.