Finnish icebreaker MSV Nordica sails the Arctic's Northwest Passage

Master Mariner Jyri Viljanen, left, captain of the Finnish icebreaker MSV Nordica and Chief Officer Harri Venalainen, navigate from the bridge through ice floating on the Chukchi Sea off the coast of Alaska while traversing the Arctic's Northwest Passage, Sunday, July 16, 2017. More than a century has passed since the first successful transit of the treacherous, ice-bound Northwest Passage by Norwegian explorer Roald Amundsen in 1906. 【Photo: AP/David Goldman]

Trainee David Kullualik, of Iqaluit, Nunavut, of Canada's northern territories, looks through binoculars from the bridge of the Finnish icebreaker MSV Nordica as it sails through ice floating on the Chukchi Sea off the coast of Alaska while traversing the Arctic's Northwest Passage, Sunday, July 16, 2017. [Photo: AP/David Goldman]

Ice is broken up by the passing of the Finnish icebreaker MSV Nordica as it sails through the Beaufort Sea off the coast of Alaska while traversing the Arctic's Northwest Passage, Sunday, July 16, 2017. The region has become a magnet for nations wanting to exploit the Arctic’s rich oil reserves and other natural resources and for scientists seeking to understand global warming and its impacts on the sea and wildlife. [Photo: AP/David Goldman]

Researcher Daria Gritsenko looks out toward the American island of Little Diomede, Alaska, near left, and behind it on the right, the Russian island of Big Diomede, as the Finnish icebreaker MSV Nordica sails along the international date line through the Bering Strait, Friday, July 14, 2017. The international date line divides the two islands, with Little Diomede sometimes referred to as Yesterday Isle and Big Diomede as Tomorrow Island. [Photo: AP/David Goldman]

The Finnish icebreaker MSV Nordica sails through ice floating on the Chukchi Sea off the coast of Alaska, Sunday, July 16, 2017, while traversing the Arctic's Northwest Passage, the treacherous, ice-bound route where Norwegian explorer Roald Amundsen made the first successful transit in 1906. [Photo: AP/David Goldman]