For Shen Quan, it was the voyage of a lifetime, a chance to pilot a ship through the Northwest Passage. For China, whose Xuelong icebreaker he helped to steer through the Canadian Arctic archipelago, it marked the beginning of a new effort to understand the waters of the far north, and the role they could one day play in delivering commercial cargoes.
The Xuelong, or Snow Dragon, left behind seven floating survey stations expected to send measurement data to scientists in China for a year, part of an effort to cast an "inspection net" over a region whose commercial potential the world's second-largest economy is beginning to probe.
Chinese vessels have already begun to regularly traverse the Northern Sea Route, the Northeast Passage that stretches across northern Russia.
But in slipping across Northern Canada, the Xuelong underscored a Chinese desire to use the Northwest Passage as well.
"By taking these two passages, we can save a lot of time," said Mr. Shen, who was vice-captain on the ship when it completed its transit in September. He spoke to The Globe and Mail after the vessel's return to Shanghai, saying he understands concerns in Canada about the damage shipping could bring to the region's environment.
Ottawa has said it allowed the Xuelong's passage on the grounds that it was a scientific expedition.
But Mr. Shen touted the benefits of Arctic shipping that could go beyond the distance reduced by skipping the Panama Canal, a roughly 20-per-cent savings.
"The large-scale use of the Northwest Passage could boost the development and utilization of the northern parts of Canada," he said in an interview.
The Xuelong is China's only icebreaker. Its maiden voyage through the Northwest Passage was hailed by state media as opening "a new sea lane for China," one that could save a full week of transit time for vessels sailing from Shanghai to New York.
Receding ice levels have made that prospect more realistic. In July, a Finnish icebreaker set a record for the earliest transit of the Northwest Passage. Months later, the Xuelong encountered just one day's worth of ice in a 39,000-kilometre journey that included the Northwest Passage.
The Xuelong sailed through the passage unaccompanied, with a Canadian pilot on board and a small contingent of Canadian researchers.
But He Jianfeng, one of the lead scientists on board the ship, said the vessel's research program was limited.
The quantity of "academic findings in the Canadian Arctic was not very huge," he said in an interview.
"We only got some basic information about the consistency of the water, the quality and temperature of it."
Some of the scientific work will continue long after the Xuelong's departure. Chinese scientists installed seven floating survey stations on chunks of ice in the Arctic Ocean that will measure temperature, meteorological conditions, airflow and indicators of ocean productivity. The devices send real-time measurements to computers in China, using batteries expected to last a year. Mr. He expects them to float into the Northwest Passage.
It's part of a broad effort to set in place what Mr. He calls an "inspection net in the Arctic," bringing together information from across the region that can "help us comprehensively understand conditions."
That information can then help to buttress decisions, Mr. He has said, on "future commercial navigation."
The Xuelong gathered data on underwater features and water depth as it sailed through the Northwest Passage, details that are "very decisive factors in judging the fitness of a passage for commercial use," Mr. He said.
Acquiring that information "we feel will push forward the commercialization process and contribute to safety improvements in that area," he said. From an academic perspective, "The navigation potential of the Northwest Passage is quite considerable," he said.
Still, it is a less attractive option for shipping than the Northern Sea Route, he said – and, he believes, future use of the passage will depend largely on decisions by the Canadian government, whose reporting requirements for interested shippers, at the moment, are complicated enough to potentially dissuade transits.
"Many commercial vessels might not even know how to apply to go through Northwest Passage at all," said Mr. Shen.
Commercial interest remains largely focused on the Northern Sea Route. In mid-September, 104 vessels were sailing either in or near those Russian Arctic waters, including at least three operated by China COSCO Shipping.
"Given the benefits of this route, I am sure it will become one of hottest passages very soon," said Li Lin, head of the shipping security department at COSCO, in an interview.
The state-owned giant made its first Arctic transit in 2013 and now dispatches five vessels through the Northern Sea Route, which "has become a normal commercial route," Mr. Li said.
For now, the window for shipments is just three months long, But with "global temperatures rising, the ice conditions in this area will get less severe, and that means each year we will have a longer window," he said, citing benefits in saved fuel and security costs for vessels that can avoid longer southern routes plagued by pirates.
COSCO has never sent a ship to the Northwest Passage, whose environment is "much more brutal," with greater amounts of ice and less developed infrastructure, Mr. Li said.
But, Mr. Li said, "I hope it will be better in the future."
With reporting by Alexandra Li