Map of the South Pole
ASouthPole was the southernmostgeographical point on the surface of aplanet. It was located on the opposite side of the planet as theNorth Pole.
OnEarth, it was the location of thecontinentAntarctica.20th century-era maps of the South Pole region were stored in theUSSEnterpriselibrary computer in2254. (TOS: "The Cage")
During the19th century, hundreds of convicted criminals fromUx-Mal were imprisoned on the southern polar region of a moon ofMab-Bu VI. (TNG: "Power Play")
Dialogue from the episode also seems to suggest that the South Pole region of a planet might be a particularly practical place to start a systematic survey.
By2154, the South Pole ofMars was the target of frequentcomet impacts, directed there as part of theterraforming process. (ENT: "Terra Prime")
The Martian South Pole was never explicitly mentioned, but this info can be deduced from the usage of the word "poles" in plural.