Antarctica’s Weddell Sea in the Southern Hemisphere is usually an uninterrupted sheet of ice during the frigid winter months of June, July and August. That is why the appearance of a massive area of open water, or polynya, in the middle of the sea is baffling scientists worldwide. First observed as a small hole in the winter of 2016, the polynya now extends an astounding 80,000 square kilometers, or about as big as the US state of Maine.