The wastelander map is a paper note found in Fallout 3.
Location
It can be obtained in the Deathclaw Chase random encounter in the Capital Wasteland, in which a group of wastelanders are fighting a deathclaw. If the Lone Wanderer assists in killing the deathclaw or if the wastelanders kill the deathclaw, a wastelander will thank the player character and give him this note. The map adds the location of Rock Creek Caverns to your Pip-Boy 3000.
Transcript
The map shows directions to Rock Creek Caverns, with the notation: "Mirelurk king's treasure chamber!"
