(CNN) — There's hope on the horizon for travelers who've been waiting to set sail on a cruise from the United States.
Sailings on numerous cruise lines are slated to embark from US ports within weeks, about 15 months after a no-sail order from the US Centers for Disease and Control and Prevention brought cruises to a halt.
Many ships are still awaiting CDC approval to sail. Since October of last year, the agency has issued a series of evolving requirements and guidelines in the form of a Conditional Sailing Order.
However, a lawsuit challenging that order from Florida Gov. Ron DeSantis is still unresolved. The two sides failed to reach an agreement in mediation, DeSantis' office said.
In the past month, as US vaccination rates have climbed, the CDC requirements have increasingly granted more latitude to ships where the majority of passengers and crew -- 95% in both cases -- are fully vaccinated.
Summer sailings with vaccination requirements, which many cruise lines have started to announce, are expected to bring some normalcy to upcoming cruises.
"When you look at what's going to happen on those sailings and what the CDC is allowing, honestly, it makes cruising look a lot like it did before the pandemic," said Chris Gray Faust, managing editor of cruising website Cruise Critic.
But vaccine requirements may be stymied by bans on "vaccine passports" in Florida and Texas, prohibiting businesses from requiring proof of a Covid-19 vaccination.
Ships hoping to sail without meeting those 95% vaccination thresholds are required to perform trial sailings with volunteer passengers to test safety protocols before being cleared by the CDC. "It obviously can be a very confusing situation," said cruise expert Stewart Chiron of The Cruise Guy website. Indeed. As with so many things related to travel during the pandemic, there's a tangle of requirements. Here's what CNN knows so far about what to expect:
Royal Caribbean's Oasis of the Seas sails past beachgoers as it prepares to dock at PortMiami on May 28, 2021.
Joe Raedle/Getty Images
When can I cruise from US ports?
Major cruise lines have started to announce sailings from US ports starting as early as late June and July.
As mentioned, the situation is in flux as cruise lines await CDC approval and the lawsuit around the sailing order remains unsettled.
Which ports are in play?
Carnival Cruise Line has announced plans to resume sailing from Port of Galveston in Texas and PortMiami in Florida with vaccination requirements. The company's announcement came on the same day that Texas Gov. Greg Abbott signed a bill banning vaccine passports.
"We are evaluating the legislation recently signed into law in Texas regarding vaccine information," Carnival Cruise Line said in a statement on June 8. "The law provides exceptions for when a business is implementing COVID protocols in accordance with federal law which is consistent with our plans to comply with the U.S. Centers for Disease Control & Prevention's guidelines."
Royal Caribbean International recently announced that six of its "ships will begin sailing from major US cruise ports in Florida and Texas in July and August," according to a press release from the company.
Those sailings will not have a vaccination requirement, the company said, contrary to earlier guidelines indicating that vaccinations would be required.
The major cruise lines are busy getting ships positioned and crews vaccinated for these and other itineraries yet to be announced and cleared to sail.
But while the companies prep and await CDC approval for cruises from US ports, some big cruise ships have arranged to sail out of the Caribbean. The first big-ship sailing in the Caribbean since the pandemic halted operations was scheduled on Celebrity Millennium from St. Maarten on June 5 with sailings on other lines to follow.
But Chiron, The Cruise Guy, cautions that those ships and sailings could move back to US ports if CDC approval comes through.
"So they could be back in Miami or Fort Lauderdale or Port Canaveral, so if I was booked on one of those ships, I would be cognizant of that and make sure that the airline will allow me to cancel and rebook my flights," he advised.
Carnival Cruise Line is working on arrangements to resume sailing out of Miami and other US ports.
DANIEL SLIM/AFP/AFP via Getty Images
Will vaccination be required?
It depends. As noted, policies vary by cruise line and ship and are still tangled in questions about vaccine passport bans.
The lines listed above for Alaska cruises departing from Seattle have vaccination requirements. Some require everyone on board to be vaccinated, effectively barring children younger than 12 who aren't yet eligible for vaccination.
Others require everyone 16 and older to be vaccinated, with plans in many cases to drop that age to 12 later in the summer as vaccinations increase in that age group. Testing would be required for younger passengers.
Recent CDC updates to its conditions for sailing have outlined relaxed requirements that would make cruises far less restrictive for vaccinated passengers.
Some ships, particularly those that sail with more than 5% of passengers younger than 12, will likely be required to go the trial cruise route for CDC approval and enforce more stringent restrictions.
The CDC is not requiring cruise lines to test fully vaccinated passengers. Testing is required upon departure and for disembarkation (on voyages of more than four nights) for unvaccinated passengers.
Check with the cruise line about your specific itinerary for details on each sailing's requirements.
Will cruises from US ports require passengers to wear masks?
The CDC's mask mandate remains in effect for transportation hubs, so masks are required in port. Masks aren't required inside cabins.
Whether to require masks outdoors is up to the cruise lines. Otherwise, the rules are likely to rest on whether or not you're vaccinated.
The CDC's latest guidance for cruise ships aligns with its broader recommendations for fully vaccinated people, the agency confirmed.
The guidance "allows cruise ship operator discretion for requiring masks outdoors, in crowds, in crew-only areas, in areas only for vaccinated passengers, and on ships with at least 95% of crew and 95% of passengers that are fully vaccinated," the CDC said in a statement.
Sailings that don't have the 95% vaccination requirements will have more mask rules for unvaccinated passengers.
What will my time aboard the ship be like?
This also depends on your vaccination status. The CDC is allowing cruise lines to designate certain areas accessible only to fully vaccinated passengers -- spaces such as casinos, bars, spas and dining areas.
This and other increased access for vaccinated passengers, "where masks and physical distancing are not required" is to be determined by "cruise ship operators, at their discretion."
Self-serve buffets are listed among areas where only fully vaccinated passengers could be permitted to gather without masks or social distancing.
Otherwise, physical distancing must be observed by unvaccinated passengers in most cruise ship spaces.
MSC is among the cruise lines that have already started sailing in Europe.
Courtesy MSC Cruises
What kinds of shore excursions will be possible?
Many cruise lines are basing their shore-excursion policies on the rules of the destinations the ships are calling on.
"Our tours extend the highest health and safety standards we're following on board. Most experiences are outdoors, and guests will be encouraged to stay with their group. Buses will be at reduced capacity and will be sanitized frequently," the cruise line's website says.
The CDC says that cruise lines, "at their discretion," may advise fully vaccinated passengers that independent excursions during port stops are OK.
What happens if the cruise is canceled or I have to change my plans?
Some cruise lines have adopted more flexible cancellation policies during the pandemic. And if a cruise is canceled, cruise lines generally offer reimbursement or future cruise credits.
But travel insurance is more essential than ever, said Angel Wilson, a travel adviser at Dream Journeys in Indianapolis.
While travel insurance didn't cover the pandemic at all last year, many companies have adapted their policies to cover Covid-related events.
But don't take coverage for Covid for granted, Chiron says. "You want to be able to clearly understand how you're covered because they're all going to be different."
A cancel-for-any-reason insurance policy offers the broadest protection in the event that any situation or uncertainty causes a passenger to rethink their trip, Wilson said.
Her best advice for cruising this summer: "Be open-minded and ready in case there are changes."