A luxury cruise ship departing Alaska on Tuesday aims to be the first of its kind through the Arctic’s Northwest Passage—and it’s very unlikely to be the last.

Billed as the “ultimate expedition for the true explorer,” the 32-day trip on the Crystal Serenity departs from Anchorage, traveling north through the Bering Strait and across the Canadian Arctic, then making stops in Greenland and the northeastern United States before docking in New York City. Prices for the sold-out excursion ranged from $22,000 to $120,000, plus required insurance coverage of at least $50,000 for emergency evacuation.

While smaller cruise ships have sailed the Arctic, the Crystal Serenity is by far the largest to make its way through a route considered nearly impassable just over a century ago. In 1905, Norwegian explorer Roald Amundsen was the first to successfully sail the Northwest Passage, calling it “that baffling mystery to all the navigators of the past.”

While the route has hardly become a marine throughway since then, more ships are making the journey. In 2012, a record 30 vessels completed the transit. Now the passage’s chief mystery lies in just how icy it will remain in coming decades as the region warms.

Sea ice also saw a milestone in 2012: It reached an all-time low, punctuating an overall decline in recent decades. As climate change opens more opportunities for Arctic tourism, shipping, and oil exploration, it is also opening more debate about the environmental and societal impact, from increased potential for oil and fuel spills to risks for habitats on which local indigenous communities depend. (See an interactive map showing the shrinking Arctic ice and rise in shipping transits.)

The ship “is navigating in uncharted territory” in this regard, says Bryan Comer, marine program researcher with the International Council on Clean Transportation. “And in some cases,” he adds, the boat is “literally navigating in uncharted territory,” since just 10 percent of the Canadian Arctic’s waters are adequately mapped.

Despite the melting trends, Arctic waters aren’t exactly smooth sailing even in August, and Crystal says it is planning accordingly. The cruise will have an escort from the R.R.S. Ernest Shackleton, a research vessel with icebreaking capability and two helicopters aboard. The Serenity itself is outfitted with ice detection radar, two ice pilots, and other safety upgrades.

The day after the Serenity leaves Nome, Alaska, the U.S. Department of Defense is assembling multiple agencies there for a five-day training exercise with the exact scenario Crystal hopes to avoid: a cruise turned catastrophic event.

“The potential number of people on cruise ships that would need rescue exceeds the capacity of most [search and rescue] response vessels and aircraft available in the Arctic,” notes a recent U.S. Coast Guard assessment. At the same time, the U.S. is facing a gap with no functional heavy-duty icebreaker that could come to the rescue in a serious crisis. It’s not yet clear whether Congress will approve 2017 budget requests for a new icebreaker and other Coast Guard improvements.

View Images As Arctic ice melts, larger ships are able to reach previously difficult to access areas. Photograph by PETE RYAN, Nat Geo Image Collection

The current U.S. approach to budgeting “is that nothing is really changing in the Arctic,” says Shiva Polefka, a policy analyst at the nonpartisan Center for American Progress who focuses on oceans. “The reality is just completely the opposite. Things are changing extraordinarily fast.” He notes that in addition to tourist ships, the Coast Guard must monitor and respond to a vast range of both legal and illegal activity, from fishing to oil and gas exploration to drug smuggling.

Beyond safety, Comer and other environmental advocates are concerned about the prospect of increased emissions and fuel spills from the rise in shipping. While the Crystal Serenity will be running on a “pretty clean” diesel as far as marine fuels go, he says, some larger cruise ships run on heavy fuel oil that would be extremely difficult to clean up if spilled.

International shipping is responsible for 2.6 percent of all global carbon emissions, according to the International Marine Organization, the UN body that oversees international shipping. That’s an amount on par with all of Germany. The IMO expects emissions to increase by at least 50 percent by 2050, and is considering, but has not yet set, global efficiency standards.

In the meantime, people in Ulukhaktok, a Canadian town of about 400, are preparing for the Serenity’s arrival. Ulukhaktok and other places in the region have long hosted smaller “expedition” cruises that tend to carry about 150 people—but Crystal’s ship will carry roughly four times the town’s population, counting passengers and crew.

Representatives from Crystal contacted the traditional Inuit community in 2014 about the area being stop on the itinerary, and Ulukhaktok has been preparing ever since with town meetings and training, says Anne Kokko, tourism development officer for Canada’s western Arctic.

Reaction to the visit was “generally very positive” in the town, Kokko says, though there were concerns about environmental impact and also the town’s capacity to handle 1,000 visitors. She says no more than 150 passengers at a time will be allowed to disembark for activities including golf, shopping, and hiking.

All the while, Kokko says, residents will be evaluating the whole Serenity experience with an eye toward potential improvements—Ulukhaktok is already on Crystal’s itinerary for 2017.