For vaccinated travelers, getting on a cruise ship in North America over the next couple of months shouldn’t feel much different than it did before coronavirus shut down the industry: They will be able to go to shows, dine at restaurants and bars, listen to live music, and, in some cases, mingle without masks.

For unvaccinated adults — if they are even allowed — it’s a different story. The experience is full of extra expenses, testing requirements, off-limits areas and other restrictions.

Welcome to covid-era cruising, in which operators are slowly welcoming passengers back with layers of protection in place to keep the virus at bay — or at least from spreading. In recent weeks, a handful of positive cases have been reported on ships in North America, though safety measures prevented larger outbreaks.

The temporary class system is proving divisive on social media, where some cruise fans say vaccinations should be required and some are accusing cruise lines of creating “second-class citizens.”

“They need to come out and say unvaccinated people are not welcome because this is getting to be a little too much,” one man wrote on the Facebook page of Royal Caribbean International CEO Michael Bayley.

Experts say the greatest tool to keep cruisers safe is the vaccine, and many voyages departing from North American ports will require everyone who is eligible to be vaccinated. But in Florida, where state law prohibits businesses from requiring proof of vaccination, safety precautions become more tricky to put into practice.

Royal Caribbean International’s first U.S. cruise, on Freedom of the Seas, leaves Miami on Friday. Vaccinated passengers will wear wristbands. Those who are unvaccinated will have a hole punched in their room card, which will be required to get into lounges, shows and restaurants.

“Since the majority of our guests will be vaccinated, there will be venues and events restricted to vaccinated guests only,” the cruise line said in a letter to guests. “We’ll do our best to create opportunities for all guests to enjoy their time with us.”

The letter said unvaccinated guests 16 and older will have to take multiple coronavirus tests at a cost of $136. The cruise line will cover the cost of tests for children and young teens.

Both vaccinated and unvaccinated passengers will have to wear masks inside unless they are sitting down and “actively” eating or drinking. Outdoors, masks are only required in a crowded setting.

Some venues or events will be designed for vaccinated passengers, and masks will not be required in those cases. There also will be showtimes set aside for vaccinated guests. The main dining room will have separate areas for vaccinated and unvaccinated reservations, with those who are not vaccinated locked in to assigned times.

When going ashore, “it is reasonable to expect that unvaccinated guests will be subject to stricter protocols than vaccinated guests,” the letter said.

Unvaccinated passengers age 12 and older on Florida cruises will also have to buy travel insurance that covers “medical, travel and other related costs for covid-19 should they test positive while on board,” the cruise line said this week.

“If you were a customer, why would you want to be one of few on a ship wearing a mask, social distancing, and getting tested — not to mention the additional costs?” said Alex Sharpe, president and CEO of Signature Travel Network, in an email. “If the State of Florida would allow cruise lines to require proof of vaccination, these guys would all do it, while finding workarounds for kids under 12 who pose a very limited health risk.”

Celebrity Cruises, also part of Royal Caribbean Group, became the first cruise line to sail from the United States when Celebrity Edge left from Fort Lauderdale this past weekend. The cruise line is also issuing wristbands to vaccinated passengers. Celebrity has committed to sailing with all crew and at least 95 percent of passengers vaccinated, a CDC shortcut to a quicker restart.

In Florida, the line said those 16 and older who decline to show proof of vaccination at boarding “will be treated as unvaccinated and subject to additional protocols, restrictions, and costs for covid-19 testing.”

That means a total of four coronavirus tests are required, at a $178 cost to the passengers. Masks will be mandatory except while eating and drinking. Unvaccinated passengers 16 and older will have seating areas set aside for them in venues including dining rooms, the casino and theater.

They must also book a Celebrity-curated tour during shore excursions and “may be further restricted from going ashore,” depending on what local governments require.

Richard Fain, CEO of Royal Caribbean Group, said he probably would require vaccinations for everyone eligible in Florida if the state allowed it. But, he said, the company has different requirements in different jurisdictions. In addition, he says adding restrictions for unvaccinated passengers is the right solution.

“And so if you are able to get a vaccine but choose not to do so, it is possible to book,” he said. “It just means that you have to follow through on the other protocols because you don’t have the protection of the vaccine.”

It’s not clear how many unvaccinated adults will even try to sail from Florida; Royal Caribbean has said its surveys show 90 percent of customers who were booking were already vaccinated or planned to be in time for their cruise. On the first U.S. cruise on Celebrity, 99 percent of the people on board were fully vaccinated, the company said. Since health guidelines are constantly in flux, the rules for the unvaccinated could change in coming months.

Further complicating matters: Florida sued the Centers for Disease Control and Prevention over its rules for cruise lines, and a judge agreed to stop the agency from enforcing its rules in the state in mid-July. It’s unclear if the CDC will come back with a narrower set of guidelines, or if cruise lines will change any of their safety measures — which are in line with the agency’s current rules — as a result.

“Let’s be honest — NO cruise line wants unvaccinated adults on their ships,” said Sharpe, the Signature Travel Network CEO, in his email. “There is simply too much at stake!”

Carnival Cruise Line has said it plans to sail Carnival Horizon from Miami with at least 95 percent of passengers vaccinated starting Sunday. The cruise line, which has CDC approval for the cruise, has not said how it plans to navigate the state law that keeps companies from requiring proof.

Norwegian Cruise Line, which does not yet have CDC approval, has said it will sail with 100 percent of people on board vaccinated.

“We’re hearing some confusion among cruisers who are still trying to navigate the various policies,” Chris Gray Faust, managing editor of the cruise news and review site Cruise Critic, said in an email. “The challenge is that different states have different laws and regulations, which means that protocols vary from line to line, and even ship to ship.”

Gray Faust said the majority of Cruise Critic readers surveyed — 80 percent — said they preferred to sail with a vaccine requirement.

“As lines continue to evolve their policies, those cruisers are monitoring the changes closely,” she wrote, “many reporting that they’re making their booking (and cancellation) decisions strictly based on those policies.”

William Schaffner, professor of preventive medicine and infectious diseases at Vanderbilt University School of Medicine in Nashville, said requiring vaccinations across the board “just makes very straightforward public health sense.”

“If you’re going to bring people together in a congregate setting, I think obliging them to be vaccinated is entirely appropriate,” he said.

But where that isn’t possible, Schaffner said, the approach of adding restrictions and other measures for unvaccinated people to protect them and everyone else on board is a reasonable solution.

“It’s getting as comprehensive in putting in public health barriers to transmission of the virus as it is possible given the constraints that they’re working under,” he said.