The Poseidon power substation PX-03 is a location in the Toxic Valley region of Appalachia.
This fenced-off power station has one shack containing some junk items. It is populated with several Scorched. There is a power box here that requires activating the Poseidon Energy Plant WV-06.
The Poseidon power substation PX-03 appears only in Fallout 76.