MIAMI (BLOOMBERG) - Guests lined up to board Royal Caribbean Cruises' Freedom of the Seas on Sunday (June 20), marking the first cruise from a United States port since the pandemic suspended operations 15 months ago.

Passengers filed into PortMiami with suitcases in tow, a sight last seen at the world's largest cruise port in March 2020. Freedom of the Seas can carry about 4,500 guests and it is expected to take about 650 on this first two-night loop, all of them Royal Caribbean employees who volunteered and were each allowed to bring a guest who is 18 years or older.

"I feel really safe with my mask. I'm vaccinated, everyone's vaccinated, so I feel really good about it," said Ms Carolina Jimenez, a 25-year-old law student who was invited along as a guest.

"It's unfortunate how long it's taken to come back, but I think that's something no one could have controlled and I'm just glad that now we're here and getting back to it."

The trip is being dubbed a "simulated voyage", designed by the Centres for Disease Control and Prevention (CDC), to essentially prove that ships are safe to sail with Covid-19 still circulating around the globe.

For the past 15 months, cruise companies have been in a state of suspended animation. They have been essentially banned from the US, the world's largest cruise market, and were saddled with the massive costs of maintaining their fleets in a zero-revenue environment. But the federal government's caution around the industry came after dramatic outbreaks at sea last year that killed passengers and crew, and taxed public-health resources.

The "vaccine obviously is a key player here and a game-changer for us and for the entire society," said Captain Patrik Dahlgren, senior vice-president of Global Marine Operations of Royal Caribbean, who spoke from the cruise terminal on Sunday.

The CDC created a two-pronged approach for cruise lines to sail again: they can run the simulated voyages or they can restart revenue cruises right away if they verify a 95 per cent vaccination rate among passengers and crew. Royal Caribbean is taking both paths almost simultaneously, with the first revenue cruise set for Saturday.

But there's another wild card in the reopening process. The state of Florida sued the CDC in April to lift the restrictions on cruises altogether, saying the industry was unfairly singled out for the strictest possible treatment, putting the jobs of many Floridians at risk.

On Friday, Florida won an injunction against the CDC rules, but US District Judge Steven Merryday put it on hold until July 18 and gave the CDC until July 2 to propose a narrower order.

The case may give cruise lines more flexibility, but it's unlikely to dramatically speed up the resumption of operations. Companies say it generally takes about three months to prepare a ship to sail, so the schedule of sailings is not likely to accelerate much in the near-term.

Free cruise

Meanwhile, volunteers have been eager to take part in the free cruise programme. Other "simulated" cruises will include volunteers from outside the company, and the cruise line says it received more than 350,000 requests to participate. The first revenue cruise - Royal Caribbean's Celebrity Edge - will sail on Saturday from Port Everglades.

Ms Victoria Ryan, a 64-year-old who started working in leadership development at Royal Caribbean shortly before the pandemic, said Freedom of the Seas would be her very first cruise and she was travelling with her long-time friend.

"I thought, 'OK, it's a free cruise, it's supporting the company and I'm going with somebody that knows what I'm supposed to do,'" Ms Ryan said. "How would I not do this?"