Antarctica

Antarctica (南極) is the Earth's southernmost continent, containing the geographical South Pole and almost entirely covered in ice.

Background
The southernmost, fifth largest and coldest continent on Earth, Antarctica is a frozen desert, with little precipitation and temperatures mostly considerably below 0°C, with mean annual temperatures in the interior lower than -50°C. 98% of the continent is covered in ice with an average thickness of around 2km.

Antarctica lacks a native or permanent human population and government, though various countries maintain scientific research stations. The regulates international activity with regards to Antarctica, promoting scientific research and prohibiting military activity and mining on the continent.

The Extraterrestrial Chaos Observatory (地球外カオス観測所) is located in Antatica.

Toaru Majutsu no Index Light Novel Volume SS2
On the second Friday of October, Misaka 19900 was sent to Antarctica, to the Extraterrestrial Chaos Observatory, one of the research organizations part of the Gemstone Mining, to rescue the Gemstone held there. During her periodic progress report, she mentioned that she had met some resistance.

World Rejecter Arc
At some point between late November and early December, before December 3rd, Patricia Birdway accompanied an Academy City sponsored research team to Antarctica, part of a study of changes in the ocean currents due to changing ice levels at the poles. While there, they encountered a parasite, later named Sample Shoggoth, which infested Patricia's body, putting her life at risk.

Coronzon Arc
While communicating with Last Order, Misaka 10782 reported that she was cooking rice cakes at the Antarctic base and was watching penguins.