There's hope on the horizon for travelers who've been waiting to set sail on a cruise from the United States.
A handful of sailings from US ports are slated to embark within the next month, nearly 15 months after a no-sail order from the US Centers for Disease and Control and Prevention brought cruises to a halt.
Most 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.
In the past month, as US vaccination rates have climbed, those 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.
Ships hoping to sail without meeting those 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:
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 on plans to launch ships with either nearly fully vaccinated sailings or trial cruises.
Celebrity Cruise Line was the first to get CDC approval to sail from a US port with paying passengers.
However, the line is still figuring out if and how that requirement would work with Florida Gov. Ron DeSantis' recent ban on "vaccine passports," prohibiting businesses from requiring proof of a Covid-19 vaccination.
In response to questions about the situation in Florida, Celebrity Cruises said "we are encouraged by the ongoing dialogue" with the CDC, local and state authorities from US ports, including Florida, and the destinations the cruise line calls on.
Which ports are in play?
Carnival Cruise Line has announced it is a step closer to sorting out arrangements and approvals to sail from Miami, Port Canaveral, Florida, and Galveston, Texas, in July. Plus Celebrity is planning to sail from Fort Lauderdale.
Numerous cruise lines -- including Celebrity, its sister line Royal Caribbean International, Holland America and Silversea -- also have recently announced plans to sail from Seattle to Alaska this summer.
That route, which would normally require foreign-flagged ships to stop in Canada according to maritime law, is possible this year thanks to the recently passed Alaska Tourism Restoration Act. It allows cruises to temporarily bypass docking in Canada en route to Alaska.
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 is 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.
Will vaccination be required?
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 vaccines are more widely available.
The CDC's conditions for sailing require that ships have vaccination rates of 95% for both crew and passengers to be eligible to sail without first doing a trial cruise. Other recent CDC updates 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 in most cruise ship spaces.
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.
On Celebrity, independent tours are "available unless locally restricted," although the line touts the safety of its own shore excursions.
"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."