LINCOLNVILLE, Maine — Earlier this winter, midcoast artists Jonathan Laurence and Anneli Skaar were given free rein of the Icelandic container ship Selfoss as it made a nine-day crossing over icy seas from Portland, Maine, to Reykjavik, Iceland.

They saw sights that were amazing, such as green northern lights rippling over the black water of the North Atlantic, and things that were strange, such as the time they spotted people hunting for puffins wearing black ski masks and carrying guns. And they were able to make their once-in-a-lifetime journey for free as artists-in-residence aboard the ship.

“The experience of being at sea is a classic setting for artists,” Skaar said.

Laurence agreed.

“Every day, looking out at the ocean, you kept seeing it differently,” he said. “At sunset, everything was sherbet orange. It was really beautiful.”

Skaar, 46, is a designer and artist of Norwegian heritage who has lived in the Camden area for about a decade and who is known for her oil paintings. Laurence, 34, a photographer and multimedia artist, grew up in Rockport and works as the creative director at the Center for Maine Contemporary Art in Rockland.

The idea for their northern adventure came about months ago, when the longtime friends met up over drinks and had the kind of “wouldn’t it be cool” conversation that usually doesn’t linger in the mind past last call. Wouldn’t it be cool, they wondered, if they could somehow combine their interests in container ships and the Arctic in a way that would let them travel and make art?

“We had all different kinds of ideas,” Laurence said.

One of those ideas was to join the Maine delegation at the Arctic Circle Assembly last October in Reykjavik. That’s how Skaar met the U.S. director of the Eimskip transportation company, which owns the Selfoss and a fleet of other vessels based in the North Atlantic.

“What would one do to get on a ship?” she asked.

She learned that for decades, it had been a common practice for cargo ships to offer free passage to artists in exchange for a work of art. In those days, cargo ships moved passengers as well as freight. That changed in the 1970s, when most cargo ships stopped taking passengers and only moved freight.

“The whole tradition of crossing the ocean has changed dramatically,” Skaar said.

But Eimskip, which moved its North American headquarters to Portland in 2013, has allowed a handful of artists to make the passage, and they were willing to extend the opportunity to Skaar and Laurence.

So the duo boarded the container ship in Portland during a February snowstorm and settled into their quarters. Onboard with them was some unusual cargo. Normally, the Portland-to-Iceland route carries such local specialties as blueberries, cranberries, potatoes and lobsters, but the artists were surprised to learn the Selfoss was loaded up this trip with the sets and vehicles for the movie “Fast and Furious 8,” which is partially set in Iceland.

“They were trying to keep it hush-hush,” Laurence said.

But it’s hard to drive a Lamborghini from California to Portland, Maine, and then have it sit in a parking lot by the port without having people notice, he said. And by the time they arrived in Reykjavik, news crews were waiting to see the boat unloaded.

That, of course, came later. What came first for Laurence and Skaar were questions about how their voyage would unfold. They knew it was possible the captain would worry about the liability of carrying a couple of artists onboard and would ask them to stay put in their cabin. Instead, the captain told them that as long as they didn’t cause any problems, they could go where they wanted on the 435-foot-long ship.

“The amount of access was insane,” Laurence said.

The photographer went everywhere to shoot photos and video for his multimedia and documentary projects, while Skaar mostly stayed indoors, writing and painting haunting scenes of life at sea.

“Jonathan was more the person who was out,” she said. “He was on the bridge, out there with his GoPro, doing amazing stuff. He was in the cranes. He was in the bowels of the ship. To have that kind of access as an artist is pretty incredible. But it’s not for everybody. It was rough. It’s not a pleasure cruise.”

The small, all-Icelandic crew treated them kindly, they said, especially after a short period of what they called “gentle hazing.” For instance, during their first evening at sea, the crew gave Skaar and Laurence such dubious regional specialties as lamb testicles in aspic — “nobody else was eating it,” Skaar said — and made them elaborate cream cakes in the form of male and female genitalia.

“We were very enthusiastic,” she said. “I think at that point they realized we had a sense of humor.”

Despite the jokes and the friendliness of the crew, the artists realized life at sea is very different from life on land.

“For all intents and purposes, it’s not that different from hundreds of years ago. This is a bunch of Vikings on boats,” Skaar said. “It was so remote. There were three days when we were completely out of range. There were so many things that could potentially go wrong, with the engines or the fuel or big things on deck.”

Laurence said the essential isolation of being at sea really struck him.

“In all directions, it’s just nothing,” he said. “You’re this little speck, and it’s great.”

Two nights before they made port, they were up on the bridge of the ship, with B.B. King’s music being played loudly.

“The moon was shining on the black, black water. There were northern lights,” Laurence said. “Really, it was the most amazing experience. Green lights, with the blues music. It was a great moment. We were pinching ourselves, saying ‘I can’t believe we’re really doing it.’”