Cruiseship in Havana, Cuba

(11:50 a.m. EST) -- With American travel restrictions to Cuba lessening, cruise passengers are eagerly awaiting word that their favorite line has added the long-off-limits island to Caribbean itineraries. So how long will it take before you see a mainstream cruise ship sail into Havana?

The answer: it depends. With infrastructure issues limiting the size of ships that could berth in Havana and a travel embargo that still needs to be overturned by Congress, a speedy timeline seems impossible. Yet with interest among cruise lines and their passengers already high, Cuba cruising could come quickly for smaller cruise ships, once barriers are removed - and one is already going.

Cruise line CEOs have spoken publicly about their desire to visit Cuba as soon as possible. In a TV interview, Norwegian Cruise Line CEO Frank Del Rio said he has itineraries locked in his "upper right hand drawer ready to go." "My unfulfilled dream is to be on the bridge of one of my ships coming into Havana harbor," he said.

"There's no question if the legislative embargo is lifted, Cuba is a tremendous opportunity," Carnival Corp & plc CEO Arnold Donald told investors in December. "There's a lot of pent-up demand to visit Cuba. It would allow us some very fuel-efficient itineraries. Also, it would provide new itineraries for those who love to go to the Caribbean."

While Royal Caribbean Cruises Ltd., which operates lines including Royal Caribbean International, Celebrity Cruises and Azamara Club Cruises, wouldn't comment on plans, Cruise Critic members reported receiving a survey from Celebrity outlining potential Cuba itineraries. The trips range from adding a night in Havana to quick four-, five- and seven-night Eastern Caribbean voyages from Fort Lauderdale to 11- and 14-night trips that combine Cuba with a traditional Southern Caribbean cruise from Miami. One suggestion even has a Havana overnight.

The ships that could do these itineraries would be limited in size. Cruise ships owned by non-American companies have been traveling to Cuba for years, although they are all considered small (under 1,000 passengers). Before Costa Cruises and Pullmantur were acquired by Carnival Corp. & PLC and Royal Caribbean Ltd., respectively, both had homeports in Havana. Among the lines that offer or have Havana as a port stop: Fred.Olsen Cruise Lines, Thomson Cruises, Noble Caledonia and Star Clippers.

No line has put itself in a better position for Cuba cruises than the appropriately named Cuba Cruise. The Canadian-based company launched in 2013 as the only cruise line offering round-Cuba sailings on the 1,200-passenger Louis (Celestyal) Cristal. The company not only calls in off-the-beaten-path ports as Antilla and Cienfuegos, but it also employs a large number of Cubans onboard, in a variety of positions including band members and as stewards and wait staff.

By developing partnerships with nonprofit organizations with "people to people" licenses, Cuba Cruise has also become the first cruise line to offer true voyages open to Americans. Americans can book now; in late March, the company is running an educational "FAM" trip so travel agents will know about the trip.

Since President Obama announced in December travel restrictions were easing, the company has experienced an onslaught of inquiries, said Dugald Wells, president and founder of Cuba Cruise.

"After the first announcement, our web traffic tripled beyond anything we have ever seen before. It was mostly Canadians booking who want to get there before McDonalds does," he explained, referring to the belief that once restrictions are limited, tourist-geared and American businesses will swarm into the country, leading to a less authentic experience.

In January when the Obama administration lifted some travel restrictions, the company's call center was overwhelmed, Wells said. US inquiries increased from about 10 percent of the total to 50 percent.

The surge in interest has led Cuba Cruise to consider extending the season to April and even add another ship: "We are looking at itineraries and other ships in the Louis fleet to see how we could make this work," he said.

Although the story of Cuba Cruise sounds like a case of being in the right place at the right time, establishing the itinerary took a lot of work and red tape -- and gives insight into the issues larger cruise lines might face if they establish ports in the communist country.

Church in Cuba city

Wells first visited Cuba in 2009 on the suggestion of his business partner, Craig Marshall. As is often the way in Cuba, Craig had a friend who knew someone who was a transport official in charge of ports on the island.

"(The transport official) said wasn't it a shame that the cruise terminal in Havana had been refurbished but no cruise lines were calling in any more," Wells said. "Well, that tweaked Craig's interest. He called me and I flew down a few weeks later to meet with the port authorities."

The meeting wasn't quite as simple as that: It took more than a month to get the suitable visas, introductory letters and documentation; things take a very long time to happen in Cuba and have to pass through a number of different ministries and sub-ministries. "We had to go through all the hoops," he said.

Wells, who has experience launching cruise lines in tough locations such as the High Arctic and Antarctica, was not fazed by the lack of infrastructure – more by the red tape.

He then took a two-week road trip around Cuba to work out what ports could realistically welcome a ship. "The infrastructure is in very bad condition, but this is not Antarctica -- at least there is infrastructure. We came to the conclusion that this was not insurmountable."

For a small ship, perhaps. The main limitation on larger ships calling in at Cuba is their draft (the distance between the waterline and the bottom of a ship's hull), Wells said. Quite simply: the ports are too shallow to accommodate large ships, and many do not directly face the sea, but are inland, meaning negotiating narrow channels and often unmapped islands.

"There are three main challenges with all of these ports: Maneuverability, depth and dredging and terminal infrastructure," Wells explained. "Even in Havana, Louis Cristal takes up the entire length of the pier."

The only way round this would be massive private investment by the cruise lines, to dredge and develop the ports: "The question is, would it be worth it?" he asked.

In his earnings comments, Carnival CEO Arnold Donald noted that the shallow draft of the Havana port restricted use to smaller ships. "But there will be investment in ports and other infrastructure required over time."

Other options include floating jetties, or tendering. With funding from Brazil, Cuba is also developing a new port an hour west of Havana called Mariel, which will primarily deal with container and commercial traffic; Wells believes this could end up catering to the larger ships.

Even if the embargo is lifted and mainstream lines do start coming to Cuba, Wells thinks there will be enough demand for all in the marketplace. "I believe strongly that the kind of product that they [the mainstream cruise lines offer] will be very different from what we are doing. We employ locals, we go to ports that large cruise ships simply could not go into."

Want to read more about cruising to Cuba? Read our Cuba Cruise Basics, our Cuba Cruise slideshow and blog posts from a 2014 sailing with Cuba Cruise. Or talk with Cruise Critic members who have sailed with Cuba Cruise on our forum).

--By Adam Coulter and Chris Gray Faust, Cruise Critic UK Editor and Destinations Editor