The sun is directly overhead on the Tropic of Capricorn in the southern hemisphere during the December solstice. It also marks the longest day of the year in terms of daylight hours for those living south of the Tropic of Capricorn. Those living or travelling south from the Antarctic Circle towards the South Pole will see the midnight sun during this time of the year.
On the contrary, for an observer in the northern hemisphere, the December solstice marks the day of the year with the least hours of daylight for those living north of the Tropic of Cancer. Those living or traveling north of the Arctic Circle towards the North Pole will not be able to see the sun during this time of the year.
Me, I can't hardly wait for the solstice. Why? Because we will have finally passed the shortest day and each following day brings more daylight. Which matters a lot when you live where I do!