A mysterious, massive hole, as large as Lake Superior or the State of Maine, has recently been spotted in the winter sea ice cover around Antarctica. This opening, known as a polynya, is the largest observed in the Weddell Sea since the 1970s. At its largest extent, this winter’s polynya had an area of open water close to 80,000km2. This marks the second year in a row in which the polynya has formed, although it was not as large last year.