The sharing economy is teaming up with the cruise industry.

In an unexpected pairing, Airbnb has joined forces with Carnival Corporation’s newest cruise line, Fathom, to offer incentives for first-time hosts who list their space on the home-sharing site.

The companies will formally announce the joint offer Friday morning, but the partnership went into effect on Monday. Airbnb and Fathom have both been promoting the deal,   which offers a $250 discount on a cruise to the Dominican Republic or Cuba for brand new hosts.

“We love that Airbnb offers a marketplace of unforgettable experiences curated by their host community all over the world,” Tara Russell, president of Fathom and Carnival Corp.’s head of global impact, said in a statement. “In many ways, we share that same passion and deliver new memories. Today’s consumers want to have unique, immersive experiences, and I’m excited that we can now creatively make this possible even further through this natural partnership.”

Here’s how the deal works: A new host in the United States — someone who has not listed a property on Airbnb before — must create a new listing, keep it active for at least 30 days, and accept and complete at least four nights of qualifying reservations. After that, Fathom says it will email a coupon good for $250 off a sailing. Cruises to the Dominican Republic start at $499 a person, though the site shows sale prices as low as $249 a person in September; Cuba itineraries are much more expensive, starting at $1,899 a person.

Representatives from Airbnb did not respond to requests for information, but Fathom vice president for human resources and corporate affairs Virginia Aulin said in an email that she wasn’t aware of any similar deals with other cruise lines.

Fathom has from the start positioned itself as a different kind of operator, initially avoiding the word “cruise” altogether. It uses the phrases “social impact cruise” and “travel deep” to describe its offerings.

That has made the product somewhat tricky to explain  — a cruise without some cruise-y elements like a casino or flashy show — and Fathom has lowered prices since it was first announced last year.

The cruise line has just one small ship based in Miami and itineraries that rotate between the Dominican Republic, where the focus is on volunteer work, and Cuba, where passengers engage in cultural exchange. The Cuban government gave permission for the line to sail from Miami in March, and cruises started in May.

Fathom’s target market is millennials, families, and older adults with disposable income who want to travel with a sense of purpose — an audience that may include travelers already comfortable with Airbnb.

“We love that Airbnb reaches millions of travelers every day,” Aulin said in an email. “We were interested in this partnership for numerous reasons, starting with our similar core values and belief in immersive travel to both being innovative brands. It was natural for us to come together and encourage people to share space with locals and travel like a local.”

The home-sharing site also lists Miami properties on the promotion page for anyone looking to book a stay before or after a cruise.

Airbnb has also made a big push into Cuba, where hotels rooms are at a premium, but that is not mentioned in the context of the offer. Fathom is often mentioned as a smart alternative for people who want to visit the island because the ship provides its own accommodations.

Airbnb suggests on the site that cruisers might be ideal hosts: “While you’re making a difference to communities in these countries, other travelers can enjoy staying in your home and community,” the site says. “The extra money in your pocket could even help you pay for the rest of your vacation.”

Photo Credit: The Fathom ship Adonia is seen sailing in Cuba. Airbnb and the cruise line are promoting a deal that gives a $250 cruise discount to new hosts. Fathom