Embark on the largest polar expedition in history: in September 2019, the German research icebreaker Polarstern will set sail from Tromsø, Norway, to spend a year drifting through the Arctic Ocean - trapped in ice. The goal of the MOSAiC expedition is to take the closest look ever at the Arctic as the epicenter of global warming and to gain fundamental insights that are key to better understand global climate change. Hundreds of researchers from 19 countries take part in this exceptional endeavour.