Fathom, the Carnival Corporation brand introduced last year with a social impact mission, is cutting back on volunteer-focused trips to the Dominican Republic to spend more time in Cuba.

The one-ship line announced Friday that it would would sail to Cuba during the weeks of Oct. 9 and Nov. 6, both of which were previously scheduled for Dominican Republic trips.

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“Since our inaugural voyage in early May, we have experienced strong, continued demand from travelers wanting to travel to Cuba with the comfort, convenience and peace of mind that comes with cruising with Fathom,” Tara Russell, the line’s president, said in a statement.

While other cruise companies including Royal Caribbean Cruises and Norwegian Cruise Line Holdings have requested permission from the Cuban government to start sailing there, Fathom is still the only U.S. operator with approval to travel from the United States  to Cuba.

Cuban officials had to give the cruise line permission to add the extra dates this fall. While Fathom said there are no plans to add more Cuba sailings this year, officials said they would consider it if the government granted more dates.

Travelers who are booked on a Dominican sailing on one of the affected weeks can either go to Cuba for no additional cost, sail to the Dominican Republic at another time, or get a full refund.

In an announcement about the new dates, Fathom highlighted the strong demand for the Cuba experience, but didn’t mention what kind of bookings they’ve seen for trips to the Dominican Republic.

“As the first cruise brand to sail to Cuba in more than 40 years, Fathom continues to experience strong, pent-up demand for sailings to that country, which is the reason for the addition of the two new sailing dates,” Russell said in an email. “The demand for sailings to the Dominican Republic continues to grow. We believed – and are now seeing it happen – that once people travel with Fathom and share their experiences, they’re eager to further brand awareness and encourage others to join as well.”

But the company has struggled to connect with the right audience to boost demand for the volunteer-oriented cruises, naming churches, private schools, and civic organizations as possible sources for passengers. The operator is offering $249 “flash sales” in September for balcony staterooms on Dominican Republic trips, significantly lower than prices it originally set.

Fathom first sailed to Cuba in May after announcing the previous July that it had received U.S. government approval for the trips. The 704-passenger Adonia visits Havana, Cienfuegos, and Santiago de Cuba with a “cultural exchange” focus to abide by laws that still govern how U.S. citizens can travel to the island. Regular tourist activities are not allowed.

Cuba was a public afterthought for Carnival Corp. though: When the cruise giant initially announced that it was launching Fathom in June of 2015, the goal was to bring service-minded travelers to the Dominican Republic once a week to do volunteer work like planting trees or pouring cement floors. It held its media launch event in a theater in New York City’s Washington Heights neighborhood, home to the largest Dominican community in the city.

Ideally, the theory went, the experience would introduce a new segment of the traveling public to cruising while making positive change for residents and organizations on the ground.

But within a month, Carnival revealed that it had won approval from the U.S. government to visit Cuba. Plans called for weekly sailings to alternate between Cuba and the Dominican Republic, though approval from Cuban officials did not come until March.

According to the company, the previously scheduled Cuba trips this year are “almost sold out” and demand is “extremely strong” for 2017. While commercial flights between the U.S. and Cuba are now happening, hotel rooms in Havana are still at a premium for travelers, and Fathom has promoted its trips as a way to see the island with room and board — not to mention paperwork — taken care of.

“Our travelers love that Fathom does all of the intricate planning so they can spend more time having a fun and memorable travel experience,” Russell said.

Photo Credit: The Fathom ship Adonia is shown in port in Santiago de Cuba. The cruise line is adding more weeklong sailings to Cuba in the fall because of demand. Hannah Sampson / Skift