Antarctica
From superman.nu: Supermanica
The southern-most continent on Earth.
In January-February 1953, when Professor Wilson divides the formula for his "four-dimensional projector" into seven parts and hides them in seven inaccessible places, one of the hiding places he chooses is the "coldest place" on Earth. According to Superman, this is the South Pole in Anarctica, "colder than the North Pole because of its higher altitude" (WF No. 62: "The Seven Secrets of Superman").
