For the private wiki only accessible to Club Penguin staff that was also abbreviated as ICE, see Internal Community Encyclopedia.
The Impenetrable Containment Environment (originally referred to as the Indestructible Containment Environment), or ICE for short, was a top-secret EPF location that was used to store important objects. It was first mentioned in issue #420 of the Club Penguin Times in a classified message from The Director of The EPF and was mentioned again in issue #436 in another hidden classified message, this time from Gary.
Parts of the Ultimate Proto-Bot 10000 (in issue #420 of the Club Penguin Times, it is mentioned they were recently stolen in a breach, but issue #436 later states they are in ICE; Protobot's arm later reappeared in the Lodge Attic)
The first hidden message, from issue #420, could be accessed by clicking the Herbert Statue in the Ask Aunt Arctic section on the back side of the paper. The second hidden message, from issue #436, could be accessed by clicking the Everyday Phoning Facility logo in the last panel of the issue's comic.
After Herbert invaded the ICE, it was moved to a different secret location to prevent him from locating it again. This process was completed on February 28, 2014. This process is what held up The EPF Rebuild.