
Although there's more than one definition of "the South Pole", the most popularly accepted one (and a travel destination) is a fixed location in the southern hemisphere at the Earth's axis of rotation, latitude 90°S (longitude not applicable). Unlike the North Pole, which is nothing but a sheet of ice floating on the surface of the Arctic Ocean, the geographic South Pole is located on solid ground, allowing a permanent research station to be built at the site of the pole itself. Although it was once an elusive goal that took the lives of many explorers, thanks to modern technology, it has been permanently staffed since 1956, and is now a destination of commercial travel expeditions.
"The South Pole" is also defined geomagnetically. This pole drifts around, and since there's nothing particularly interesting about it other than perhaps watching your compass not work, it receives no visitors. There's also a southern pole of inaccessibility, the point in Antarctica farthest from any coastline. This is a fixed location (barring major sea level changes that might redefine coastlines) at 85°50'S 65°47'E, but as the name suggests, travel to this point is generally impractical.
It's tempting to say that the climate at the South Pole is consistently bone-chilling cold, but it is not. In December it is bone-chilling cold, with an average temperature of around -28℃ (-18℉). In July it is astonishingly bone-chilling cold, with temperatures sagging to -80℃ (-112℉). (Note that there are no "day-time highs" or "night-time lows" in these figures, because the sun only sets and rises once each year.) Snowfall is scarce; since weather systems rarely penetrate into inland Antarctica and because the temperature is often too low, hence its desert status. The existing snow does drift, however, with winds averaging a modest 12 knots. (At these temperatures, calculating wind-chill factors is fairly pointless.) Antarctica is the coldest, windiest continent on Earth and as such an expedition there surely carries a risk of danger. Freak snowstorms and white conditions (both caused by high winds) can affect South Pole expeditions and have buried the ceremonial South Pole markers (they have to be bulldozed out of the snow usually).
The terrain around the South Pole is consistently flat. Ice is fluid enough to settle to a flat surface if left undisturbed, and the underlying rock isn't geologically active, nor is there any rainfall to sculpt it.
Antarctica is (for obvious reasons) the least-visited continent, and the South Pole is (because it is not accessible by sea) the least-visited site in Antarctica that is nominally "open to tourism".
Most expeditions take place in November thru January, during the Antarctic summer/day. They generally launch from Punta Arenas at the southern tip of Chile, stop at Patriot Hills camp in the Ellsworth Mountains on Antarctica, and make the final leg of the trip by air as a day trip to the Pole itself. Some expeditions drop travelers well short of the Pole, leaving them to finish on the ice.