Take these coordinates - they point to a backpack next to a stalker's corpse under the pipeline.
― PDA message
Backpack under pipeline is a stash located in the Great Swamp in Clear Sky.
Overview
The stash can be purchased from Nimble and is located southeast of the Pump station. The backpack is directly under the pipeline where a corpse lies in almost a sitting position.
Gallery
Southwest of the Pump station.
Look for a corpse sitting up against the pipeline.
Easy access from the south side of the pipeline.