A US icebreaker has begun a voyage that will include a Northwest Passage transit

The Coast Guard Cutter Healy will also visit Greenland and sail home to Seattle via the Panama Canal, circumnavigating North America.

The U.S. Coast Guard Cutter Healy is headed for Arctic waters — and a rare trip through the Northwest Passage that will end in a circumnavigation of North America.

The medium-duty polar icebreaker departed for the voyage from its homeport of Seattle earlier in July, the Coast Guard said in a press release Friday. On Monday, the ship was in port at Dutch Harbor, the U.S. deepwater port nearest the Arctic, according to the navigation tracking site MarineTraffic.

Coast Guard officials first announced plans to sail the Healy through the Northwest Passage in March. Canada and the United States have long differed over the status of the Northwest Passage. Canada regards the channels that make up the route as internal waters, subject to its regulation, while the U.S. sees them as international straits, and therefore open to global navigation.

Though the U.S. had planned to conduct what are known as a “freedom of navigation operations,” or FONOPS, in the Arctic in 2019, potentially in the Northwest Passage, those plans were put on hold. And at the time it was announced, a Coast Guard spokesperson stressed that the Healy’s voyage this summer was coordinated with Canada and “definitely not a FONOP.” Officials then said the mission would involve scientific research in conjunction with institutions from Canada and Denmark, and include operations in Baffin Bay and a stop in Nuuk, Greenland.

The most recent release also said the Healy would “promote U.S. interests along the U.S. and Russia maritime boundary line,” though it did not specify in what way. Last winter, while the Healy was undergoing repairs from an electrical fire, the Polar Star, the Coast Guard’s only operational heavy-duty polar icebreaker, conducted rare joint patrols in the Bering Sea with the Russian Border Guard.

After the Healy’s Arctic mission is complete, the ship will return to Seattle via the Panama Canal, to complete its circumnavigation of the continent, the Coast Guard said.