Answer: New Zealand Standard Time

For the vast majority of locations on Earth, the local time is set based on the longitude of the location so that the clock is (more or less) in sync with the sun. In this fashion, somebody living in London experiences the same kind of noonday sun that somebody living in New York does.

When it comes to setting the time at the South Pole though, the conventions sort of fly out the window. Not only are there no real longitudes at the pole (as you’re sitting at the location where they all converge), but the sun only rises and sets once a year.

So how was a time zone decided on? The only continually occupied location at the pole, the Amundsen-Scout South Pole Station, observes New Zealand Standard Time because it is extremely practical to do so. The South Pole Station is resupplied by McMurdo Station (located on the edge of the continent), which is in turn supplied by flights coming in from Christchurch, New Zealand. When you only have a single supply chain, it makes perfect sense to synchronize all your clocks to the same time your supplier is using.