Everywhere on earth south of the Antarctic Circle, the planet experiences at least one full 24-hour period of no sunrise/sunset annually.
On the Antarctic continent, the least amount of sunlight is available during the winter season.
There are no 'rivers' in Antarctica, unless you consider glaciers as flowing rivers of ice. You can review the lists, below, and identify the longest glaciers in Antarctica.
Lambert Glacier in Antarctica
The Antarctic Peninsula.
Antarctica has its short days and long nights in June which is when it is wintertime there To see when Antactica has its longest days and other stuff about it, see the related link
cold for short days and longer nights
Mercury. (It is NOT Venus).
Antarctica has the longest coastline among all the continents.
The southern lights, or aurora australis, can be seen from Antarctica during the austral winter months, from March to September. The best time to view the southern lights is during the peak of the Antarctic winter, around June and July, when the nights are longest and the skies are darkest.
vinson massif
what time of year does antartica have its shortest days and longer nights
The Lambert Glacier in East Antarctica, is the longest glacier in Antarctica and the world. It is about 40 km wide and about 400 km long. It drains nearly 8% of the Antarctic Ice Sheet into the Amery Ice Shelf.
You may be thinking of the Antarctic Peninsula.