The Impenetrable Containment Environment (alternatively named Indestructible Containment Environment), or I.C.E. for short, was a top secret EPF location. It was first mentioned in issue #420 of the Club Penguin Times in a classified message from The Director of The EPF. Another hidden classified message, this time from Gary, appeared in issue #436.
After Herbert invaded the I.C.E., 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.
Gallery
The first classified message regarding I.C.E., from issue 420 of the Club Penguin Times
The second classified message regarding I.C.E., from issue 436 of the Club Penguin Times