SYDNEY, Australia — After months of locked-down borders, countries that have stifled the coronavirus are trying to choreograph a risky dance: how to bring back visitors without importing another burst of uncontrolled contagion.

Estonia, Latvia and Lithuania dropped restrictions for each other on May 15, while keeping out everyone else. Australia and New Zealand are planning to revive unrestricted flights within their own “travel bubble,” which Fiji, Israel and Costa Rica are clamoring to join.

In China, cities are fast-tracking corporate charter flights, though Beijing remains sealed off. In Cyprus, tourists can get in only if they carry health certificates proving they tested negative for Covid-19.

International travel has always been a proxy for trust among nations and people, but the pandemic has poisoned the air. Now, relationships are being rebuilt under enormous economic pressure, with a wary eye on a pathogen that is not going away anytime soon.

The calculations of risk and reward vary. Some countries are eager to find ways to reopen doors to people from places, like the United States, that are still struggling with the virus but are important sources of trade and tourism. Others are scanning the globe for safer, if less lucrative, partners.

The challenge for every country involves both epidemiology and psychology. Trips for business and pleasure must have enough restrictions to make travelers feel safe, but not so many that no one wants to bother.

“We’ll all get back to moving again, but in a different way,” said Scott Tasker, a general manager at Auckland Airport in New Zealand. “This is a global shock to the aviation and tourism industry, the likes of which we’ve never seen.”

In interviews, airport executives, tourism officials and travel analysts, along with investors, doctors and government officials, described a momentous effort that is just starting to coalesce.

They predicted a mix of precautions and incentives. Masks, fever checks, contact-tracing apps and even coronavirus throat swabs will make travel more agonizing, even as discounts and smaller crowds soften the blow. A reduction in flights will mean more connections and longer journeys, testing travelers’ patience.

The baby steps toward a reopened world start with the healthy — the nations that have low rates of death and few active cases.

The Baltic countries have gone first, and Australia and New Zealand are following a similar path. But even for countries with close ties, it is like starting from scratch.

Border agencies, airports, airlines and health officials in Australia and New Zealand have spent more than a month trying to work out a proposal that would let travelers avoid the mandatory 14-day quarantine now in place for a smattering of international arrivals. They hope to have the system up and running by September.

Mr. Tasker, the Auckland Airport official, said the biggest hurdle was making sure that local transmission of the virus was as close to eliminated as possible. Beyond that, travelers can expect new protocols and constant reminders about social distancing, health and hygiene from booking through return. Australia’s coronavirus tracking app, COVIDSafe, could also be used to share location data between both countries.

If it works for the two island neighbors, the bubble could grow to include other locations.

Many European countries are also starting out with a restricted guest list. Denmark and Norway are opening to each other on June 15, for example, but are excluding Sweden, where a looser lockdown has let the virus proliferate.

With every phase of reopening, officials said, more movement means more risk and more work, for governments but also travelers.

“It’s just not going to be as free-flowing and spontaneous as it once was,” said Margy Osmond, the chief executive of Australia’s largest tourism association and co-chair of the group working on travel between that country and New Zealand. “I don’t know that it will be more expensive — the jury is still out on that — but it will mean the average traveler has to take more responsibility.”

So will everyone else involved with travel.

At many of the world’s busiest airports, which are just starting to see upticks in traffic after declines of 90 percent or more, all employees now wear masks and gloves. In Dubai’s giant mall of an airport, all arriving passengers are now scanned for fevers with thermal imaging technology, which is also being rolled out at transport hubs in Europe and the United States.

Airlines are instituting their own forms of protection. All over the world, they are reducing food and drink service (further diluting its charms) and prioritizing masks for everyone. Ryanair, the popular European budget carrier, now requires that passengers ask permission to use the bathroom so that lines do not form.

Smaller-scale collaborations are also beginning to work out what to do with travelers from higher-risk countries.

In June, 500 volunteers will fly from San Francisco to Taipei, the capital of Taiwan, as part of a study by Taiwanese officials and Stanford University. The passengers will be tested for the virus before boarding and then three, five, seven, 10 and 14 days after arrival. Researchers hope to figure out what is the latest day a positive test could emerge — with the goal of shortening the current 14-day quarantine.

“The most important thing is for travelers to feel safe to fly again, and for the countries receiving the travelers to feel that they have done a good job in protecting their borders,” said Dr. Jason Wang, director of the Center for Policy, Outcomes and Prevention at Stanford Medicine.

Some companies are already embarking on journeys of their own. In April, business travel was the first thing to open up between South Korea and some parts of China. Last week, a group of German businesses chartered a flight to Shanghai with 200 workers, some being “fast-tracked” with proof of a negative test and an abbreviated quarantine.

Private jet use is also surging — why share a plane if you don’t have to? — but even for the 1 percent, first-class treatment may include testing before you go, masks on board and a couple of days locked in quarantine, followed by more screening. A passenger on that flight from Germany tested positive for the virus on Sunday.

No wonder analysts expect international travel to recover with the speed of a casual stroll.

“We think short-haul international comes back in the next two to three years, but the long-haul stuff comes back in five to seven years,” said Helane Becker, managing director and senior airline analyst at Cowen, a New York investment bank.

Even that may be optimistic. While places like Sicily and Japan are looking at flight or lodging subsidies to lure visitors, long flights in a mask have limited appeal. And the white-collar crowd — in finance, in consulting — that once traveled without much thought has discovered that it can get the job done without being away from home for 100 or more days a year.

Old habits in corporate travel will eventually return, said David Barger, the former chief executive of JetBlue, but only after new norms and stability emerge.

“If you’re the person who travels a lot, you want predictability,” he said. “Until there’s certainty, you’ll have people saying, ‘I’ll do the Zoom call, or instead of six trips a year, maybe I’ll do two.’”

So perhaps the real return to travel will begin closer to home. In the car.

For the foreseeable future, places that were popular with both foreign tourists and locals — Byron Bay in Australia, Disney World, the French Riviera — will probably look more like they did in the 1970s, before deregulation made air travel more affordable. Think of highways with cars packed full of gear and children in the back asking “Are we there yet?”

Some countries, including New Zealand, have set aside money for a tourism reset, encouraging providers to serve local customers and higher-value visitors.

Cruise ships, whose image has been battered by coronavirus outbreaks, are also rapidly adapting, with increased spacing among everyone on board.

But some regular travelers have learned that they can be perfectly happy not traveling at all.

Paul Davies, a respected physicist who teaches at Arizona State University, spent years bouncing around to science conferences and lectures. But when the pandemic hit, he was in Sydney, Australia, where he used to live — and that is where he was quite happy to remain.

He noted that during World War II, when travel was severely constricted, great discoveries occurred as the world’s sharpest minds stayed home and mulled the universe.

“Many of us have been saying for years that we have too many committees, far too many meetings and not nearly enough quiet thinking time,” Professor Davies said.

“Jetting around the world and doing all these meetings — personally I find myself a bit uncomfortable doing that now. And I think that if people get more into the habit, this could be a better way of conducting our affairs.”

In February, news from the Wynn Las Vegas included plans for Valentine’s Day (among the offerings: a “Lover’s Menu for Two”) and National Margarita Day (four new cocktails).

What a difference a pandemic makes.

Three months later, the casino resort announced a much more sober initiative, the “Wynn Las Vegas Health & Disinfection Program.” The 28-page memo lays out how the 2,700-room property will address health and hygiene when it reopens. Out with mezcal and barhopping; in with thermal cameras, elevator capacity limits and disinfection protocols for the Chipper Champ, a chip-sorting machine.

According to the American Hotel & Lodging Association, an industry group, the coronavirus outbreak has cost hotels in the United States more than $23 billion in room revenue since mid-February. As these properties prepare for a new operational reality — one that must balance federal, state and local laws and consumer anxiety about getting sick — the world’s largest hotel companies have all come forward in recent weeks to announce new cleaning playbooks.

“The first question that comes to mind when someone’s making the decision to book is: ‘Am I going to be safe?’” said Suzanne Markham Bagnera, Ph.D., assistant clinical professor and chair of the undergraduate program in the School of Hospitality Administration at Boston University. “Cleaning has traditionally been a back-of-the-house or behind-the-scenes tactic, hotels are now needing to bring that to the center stage.”

Program names riff on the hottest word in hospitality right now: clean. There’s Hilton CleanStay, Choice Hotels’ Commitment to Clean, Best Western’s We Care Clean, Omni Safe & Clean and IHG Clean Promise. Four Seasons has Lead With Care, Wyndham has Count on Us, Mandarin Oriental has We Care, Rosewood has Commitment to Care. Marriott launched a Global Cleanliness Council; Hyatt, a Global Care & Cleanliness Commitment. Topping it off is the American Hotel & Lodging Association’s Safe Stay, a list of general industry recommendations.

“It’s not about what these names say outright — it’s about what they signify,” said Anthony Shore, a linguist who helps name products and companies. “We used to take a clean hotel room for granted and hope that hotels would deliver. But now, because we associate the word ‘clean’ with something that is virus-free, it has become more loaded than it used to be.”

Although there are no hotel-specific disinfection guidelines from the Centers for Disease Control, the agency’s general Covid-19 resources — including everyday steps for employers and best reopening practices for businesses — has offered a foundation for hotels as they’ve sought to create their own. Many of the new cleaning plans include a consultancy with a leading medical organization, products and technologies from Ecolab (a major hygiene and safety company), some element of social distancing, increased disinfection of guest rooms and public spaces, and a commitment to procure and test new technologies like robots and ultraviolet light.

Guests will immediately notice the disappearance of the breakfast buffet, the decluttering of nonessential room items like throw pillows, and the wearing of masks and other personal protective equipment by staff.

More cleaning, more jobs?

Mr. Shore said the new batch of nomenclature from hotel marketing teams doesn’t suggest a higher degree of cleanliness or a significant departure from the pre-Covid era. But these measures, if implemented fully, will substantially alter how hotels operate.

“This is completely going to change the role and realm of housekeeping,” Dr. Bagnera said. “With occupancy rates so low, now is the perfect opportunity for hotel general managers to work with their teams and make sure they’re mapping out how they’re going to clean the rooms, how they’re going to be efficient and how they’re going to keep their employees safe.”

In recent years, many housekeeping tasks were streamlined or replaced. Complex new cleaning protocols could revitalize those jobs, and perhaps add new ones, particularly as occupancy levels rebound.

For Unite Here, a hospitality workers’ union with 300,000 members in North America, the new guidelines raise questions about what will happen when hotel workers clock back in. More than 95 percent of its union members are not working as a result of the pandemic.

“These new measures — and the reality that they must be adhered to well into the future — point to a need for more workers across the board,” said D. Taylor, Unite Here’s international president.

Best Western predicts that its “We Care Clean” program — which includes more disinfection of touchpoints like faucets and door handles — will increase the time it takes to clean each room by 50 percent.Industrywide, the use of new disinfectants — which must sit on a surface for a certain amount of time in order to be effective — will force an adjustment to the flow in which rooms are serviced.

Playbooks, not strict rules

Whereas Wynn’s lengthy memo gets into the weeds about what will happen at one stand-alone casino-resort — “Addition of inserts into golf hole cups to allow easy removal of balls” — companies with thousands of hotels can’t offer that level of detail. Rather, their new cleaning guidelines are meant as overarching navigational tools. They’re guidelines and best practices, not strict directives.

“CleanStay” will begin rolling out to all Hilton brands worldwide in June. Marriott is taking a phased approach to its rollout over the next 30 to 90 days, and to all 30 brands, including The Ritz-Carlton.

But most big chains do not usually own, and often don’t operate, the hotels bearing their names, meaning it’s up to individual franchise owners to fund supplies, training and marketing.

That makes oversight a challenge. Best Western will have a system of self-auditing for its 2,200 North American hotels; general managers will be asked to keep a “We Care Clean” checklist on file. Wyndham will kick-start “Count on Us” by financing and shipping the first round of masks, hand sanitizer and disinfectant wipes to more than 6,000 hotels and allow them to defer repayment until September. All of Hyatt’s managed and franchised hotels — more than 900 globally — will appoint “Hygiene Managers.”

Hygiene gets personal

Boutique hotels could face additional hurdles as they seek to marry cleanliness with individual expression.

Quirk Hotel, Charlottesville, in Virginia, opened in early March only to temporarily close less than two weeks later. As it preps for a June reopening, its leadership is considering ways to adhere to Hyatt’s global guidelines (Quirk is part of Destination Hotels, a Hyatt brand) without losing the identity suggested by the hotel’s name. Employees will wear light-pink masks — a nod to the hotel’s logo and lobby décor — custom tailored by a local garment maker; no-touch restaurant menus will double as clever, artistic table centerpieces.

“We are doing everything possible to go beyond simply complying with the new requirements from our parent brand, Hyatt, and the governing state of Virginia to ensure the heart and soul of our property stays intact,” said Matthew Brink, the hotel’s general manager.

Personal touches go even further at fully independent hotels. At Old Edwards Inn & Spa and Half-Mile Farm, sister luxury hotels in Highlands, N.C., staff members are undergoing eye-expression training to decipher the needs and emotions of guests wearing face masks. The Inn at Little Washington, in Virginia, is using life-size mannequins to fill out the state-mandated socially distanced seating at its Michelin-starred restaurant. Ocean House, on the Rhode Island coast, is supplanting its nightly happy hour at the bar with a canape-and-cocktail cart that pushes from room to room.

The New Responsibilities of Guests

These visual cues will be paramount as hotels big and small rebuild consumer confidence. Data from the U.S. Travel Association and MMGY Travel Intelligence suggests that Americans right now consider vacation rentals safer than hotels. In a recent survey of nearly 4,600 respondents, the management consulting firm Oliver Wyman found that improved health and cleaning is the chief factor impacting the decision to stay at a hotel. That’s why most of the new guidelines encourage public-facing elements like social-distancing signage, seals identifying that a room has been disinfected, Plexiglas partitions and more.

“Guests will be interested to know how their room is cleaned, how often it’s cleaned and who is responsible for maintaining a safe environment within the hotel,” said Tim Chatfield, the founder and chief executive of Jitjatjo, an online hospitality industry platform.

But in order for any of these new programs to work, industry experts and hospitality worker activists believe that health and hygiene must become give-and-take.

“Hotels are asking guests to wear masks, distance themselves, wash their hands and use sanitizer or wipes before going into the elevator,” Dr. Bagnera said. “It’s like: ‘Come in and we’ll take care of you at a hundred percent — but you’ve got to participate in the new process as well.’”

A store near Hartford, Conn., just sold its last aboveground pool. The owner said he could easily sell 100 more.

Sand, a material crucial for erecting pools on a smooth and level surface, is hard to keep in stock for more than a few hours at one bulk supply company in New Jersey.

Casey Freeman, a nurse in Nashville who made a do-it-yourself video about how to create a pool out of a stock tank — commonly used as a water trough for cattle — has been deluged by requests for material and help with installation.

“People in New York City can’t understand why they can’t find a 10-foot tank,” said Ms. Freeman, 39. “And I ask them: Are there cattle ranchers near you? And they just don’t understand.”

Staring down the barrel of a long, hot summer — with vacations on hold and many camps, playgrounds and public pools closed because of the coronavirus — homeowners are hunting for creative ways to stay cool, active and sane.

For some, not having to pay for camps or vacations means more money to spend on other things.

Landscapers and retailers say sales of gardening soil, mulch and firewood — for fire pits — are soaring. Trampolines are hard to come by. And swing sets at one large Long Island distributor that has been taking orders online and by phone, Backyard Solutions, have been out of stock since March.

“People are just getting their names on the list and throwing down 25 percent and hoping to get it by August,” said Melissa Smith, a sales representative for the swing set distributor. “If we had someone here 24 hours, I guarantee they would sell all day and all night.”

And then there are the pools.

High-end in-ground varieties remain in demand among homeowners with deep pockets and the luxury to wait months for permits and construction.

But it is the aboveground versions that are the hottest items at many pool stores, both because of their relative affordability and ease of installation.

Of course, in a country where 40 million workers have filed unemployment claims since mid-March, even low-priced pools are well out of reach for the many people struggling to pay rent and grocery bills. A pool is decidedly not a perk for everyone.

And they are a mere fantasy for those living in cramped apartments. Aboveground pools require ample space, which make them more viable for suburban and rural homeowners, who are driving the frenzied market.

“Sales are up exponentially,” said Steven Metz, president of Central Jersey Pools in Freehold. “Triple what it was last year.”

The wait time for purchase and installation is now stretching into July, he said, and calls are coming in from as far away as Wisconsin. One woman asked the store to overnight a pool to Long Island.

Prices for metal-frame pools, including installation, can range from about $3,500 to $15,000, Mr. Metz said, depending on size and sophistication. (Some can be sunken partially into the ground with built-in steps, for example, much like in-ground pools.)

“You skip your vacation, you can pay for your pool,” said Paul Healy, the owner of Splash Pool Supply in South Windsor, Conn., who sold his last remaining aboveground pool last Wednesday. “If I had a crystal ball, I would have ordered a lot more.”

Since mid-April, Google searches for aboveground pools have climbed steadily, outpacing the number of inquiries each spring for the last five years by about 300 percent.

“It’s really been 48 states and Europe,” said Doug Hollowell, the owner of one of the nation’s largest aboveground pool manufacturers, Doughboy Pools in Arkansas. “We’ve seen pool packages shipped to places we never thought they’d go.”

A man who answered the phone at Aquasports, a New Jersey pool manufacturer, said the company was “under siege.”

“It’s like the toilet paper and the water and the masks,” he said before declining to give his name.

Pandemic-related supply chain problems have intensified the shortage.

Doughboy buys most of its parts in the United States. But it relies on electric motors sold by companies in Mexico and China to power its pool pumps, and Mr. Hollowell said orders were significantly backlogged.

Workers at his plant in West Helena, Ark., which is now operating 24 hours a day, seven days a week because of the increased demand, have had child care issues related to school and day care closures. “We’re begging for employees,” Mr. Hollowell said.

The factory for an even larger pool manufacturer, Wilbar International in Hauppauge, N.Y., has been closed as part of the governor’s shutdown order.

“We’re hoping and praying that they get back up quickly because it will relieve this crazy demand,” Mr. Hollowell said.

While the explosion in sales is certainly good for business, Mr. Hollowell said he worried about the added risk of drowning, and he urged parents to remain attentive. “The only way to prevent accidental drowning is constant adult supervision,” he said.

Jackie Dahrouge, a preschool teacher from Belmar, N.J., began her hunt for a backyard pool soon after the start of the coronavirus lockdown.

She found one online and began clearing space for the 12-by-24-foot pool that she considered a down payment on a happy summer in an unpredictable world. If beaches close because of crowds or a spike in virus cases, her 8-year-old daughter and her extended family would still have somewhere to swim, she figured.

Two weeks later, the store notified her the order could not be fulfilled.

“We called every pool store. All the way into New York,” said Ms. Dahrouge, who lives less than a mile from the beach. “I even called companies in California.”

She eventually found one on eBay — in Oklahoma. It was shipped by freight truck, and relatives and friends helped to set it up on Saturday.

She said her family paid for it with money that would have otherwise been spent on a springtime vacation to Tennessee, which was canceled.

“We didn’t go away. We didn’t have a vacation,” Ms. Dahrouge said. “We said, ‘Let’s spend it on the yard.’”

Dominick Mondi, executive director of the Northeast Spa and Pool Association, said it was too early to put a precise value on the boom. But sales, he said, have been “considerably above pace for this time of year.”

Two weeks ago, Andriano Placencia and his wife, Cecilia Ordonez, purchased the house they had rented for 20 years in East Windsor, N.J. Mr. Placencia, 41, said he had long dreamed of owning a pool, and watching his two children and his grandchild swimming outside.

The virus convinced him that it was time to make good on that dream.

“The beaches are open, but I don’t like to go there as much,” Mr. Placencia, a floor installer, said as he shopped last week for a pool. “There’s more security in your house.”

Kathryn Garrecht, 71, had no plans to replace her pool after it was destroyed this winter by a falling tree.

Then the pandemic upended everything, and her four grandchildren — including a 3-year-old she babysits daily and a 14-year-old who is autistic — needed somewhere to play.

“You know, what with the Covid-19, going to the beach was a little sketchy,” she said. She ordered an 18-foot round pool in April, and it was installed in her backyard in Wall, N.J., several weeks ago.

The desire to make indoor and outdoor improvements is driving a nationwide uptick in sales at independent home supply and hardware stores, according to Dan Tratensek, vice president of the North American Retail Hardware Association. In a recent survey, nearly three quarters of its members reported an increase in sales during the pandemic.

At the Yard in Scotch Plains, N.J., which sells mulch, sand and firewood in bulk, sales are up by about 35 percent, according to an owner, Kenny Midrano. He hired five extra workers just to split logs.

“Usually it’s 10 cords of wood a month this time of year,” he said. “We’ve been doing 150 to 175 cords. Everyone’s hanging outside at the fire.”

In early May, Joe Colangelo, chief executive of Boxcar, an app-based parking and transportation company, had a hunch.

“I bet pools aren’t going to open,” Mr. Colangelo said. “Let’s see what deals I can get on bulk prices.”

Boxcar’s revenue stream had evaporated in March when most commuters began working from home. The company pivoted, and is now arranging grocery pickups, organizing drive-in movie outings — and selling pools.

Last Tuesday night, Boxcar put 30 inflatable-style pools for sale on its app. They were gone by 7 a.m. Wednesday, Mr. Colangelo said.

One buyer, Nancy Colacitti, 46, said she had tried to purchase a pool online for her two sons.

“All sold out,” said Ms. Colacitti, of Cranford, N.J. Then she saw Boxcar’s promotion.

“And that was perfect,” she said. “We can stay safe at home, keeping the social distance. We are bringing the beach to us.”

Chang W. Lee contributed reporting.