Fallout 3 locations project
The Yao Guai Den is a section of the Yao Guai Tunnels containing the Sneak bobblehead.
To find the Sneak Vault Boy Bobblehead, turn north at the first major intersection inside the Yao Guai Tunnels and follow the tunnels to the door to the Yao Guai Den. Once inside the Den, walk straight ahead to the central pillar, and then turn left. Immediately look for the natural stone ramp that leads along the eastern edge of the cavern, overlooking a crescent-shaped pool of water. At the base of the ramp is a Metal Box with the bobblehead standing on top of it.
You can find a Note on a dead Settler which explains what has happened in the Yao Guai Tunnels. It says: Nan needs to cut it with these crap stories about beasts lurking in the depths of the cave. Nonesense is scaring the children. I've made up make-shift barriers until we have time to make permanent ones. The barriers are there more for my own sanity than anything. We've been in this cave for a month now and we've finally been able to get everything settled. It's nice to be inside and not have to worry about raiding parties overrunning our camp at night. We're safe here and that's all that matters at the moment. Obviously the poor settlers were mistaken and overrun by the Yao Guai.