In the next few weeks, your wiki will be migrated to a Fandom.com domain. Learn more here.
It can be obtained in a 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 PC and give him this note. The map adds the location of Rock Creek Caverns to your Pip-Boy 3000.
The map shows directions to Rock Creek Caverns, with the notation: "Mirelurk King's Treasure Chamber!"