After crossing the level's first acid pit, you can crouch underneath the broken wall on your left to find another hidden den.
What's inside?
Some Aperture Science posters, accompanied by the usual scrawlings (made slightly more difficult to see by the red writing being on a brown wall):
"She's Watching You" with a drawing of a surveillance camera
A drawing of a cake with a line through it
"Help"
Plus the usual tins of beans, jugs of water, cartons of milk, a makeshift stove, and a bucket. If you've beaten the game, you can also find the chamber's first radio.
There's also an upstairs area with some walkways, but the door there can't be opened.
And last but not least, a massive pit of acid. There's some railings next to it, but it's still far too easy to fall in!
Guide help
This is the low-spoiler guide for "The third den" puzzle in Portal. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.
Hi! I have written video game guides since 2018. Any money I make here will go towards improving my equipment so I can make the things you enjoy even better (and faster!)