The plaster-cast heads of Dionysus were back. The unblinking blue Mati evil eyes and Parthenon refrigerator magnets hung once more outside the souvenir shops of Plaka and Monastiraki, where shopkeepers tended to rows upon rows of leather sandals, silver meander rings, dried spices and Cretan mountain tea. The tourists were back, too, if not quite so many as one might expect in the historic heart of Athens on a similarly brilliant, blue June day of years past.

They strolled Pandrossou Street in their masks, filling the restaurant terraces that line the sinuous alleyways of the Psiri neighborhood as the sun set to share plates of mashed fava beans, grilled octopus and Greek salad. The streets hummed with the din of voices and clinking glasses, but no music. Music would not be allowed for one more week. The masks were mostly off now, revealing contented, sun-dazzled faces — and maybe the slightest flicker of lingering unease.

On May 14, Greece officially opened its doors to vaccinated and Covid-negative visitors from much of the world, including the United States. In doing so, the country jumped ahead of a broader European Union reopening at a time when coronavirus cases remained high and more than three quarters of the Greek populace was still unvaccinated. It was a gamble Greece couldn’t afford not to make, after seeing its economy shrink a staggering 8.2 percent in 2020. The country welcomed only 7.4 million visitors last year, compared to 34 million in 2019, when travel and tourism accounted for more than 20 percent of the gross domestic product.

“It’s beyond wanting. We need the people to come back,” said Chara Lianou, an Athenian with dyed-lilac hair and matching acrylics who was serving coffee at Kafeneion 111 in Monastiraki. “The economy needs it, and going back to work, you feel like you are doing something. The communication with the people, even the bad ones, they make my day,” she said as a new group of patrons settled in beside us.

I arrived in Athens on a Saturday in early June after a brief scare in which I very nearly missed the 24-hour deadline for electronically submitting a Passenger Locator Form, or PLF, one of several new measures required for anyone entering Greece from abroad. At least six people were refused boarding on my flight from Berlin for failing to submit the PLF or doing so incorrectly. Anyone entering the country from abroad must also have proof of vaccination or a negative test (not older than 72 hours for P.C.R., or 48 hours for antigen) and medical personnel are stationed at the airport to perform tests as needed at mobile laboratories. When I visited, there was a mask mandate and social distancing in all public places, even outdoors, though it’s since been narrowed to indoor and very crowded outdoor spaces.

For the unvaccinated, there’s a further element of uncertainty.

“You’re always a bit worried,” said Sonia Higuera, a Colombian pharmaceutical representative visiting Athens from her home in Switzerland, where only about a third of the country is vaccinated. “Like what happens in the event I’m positive and I have to stay for 14 days in this country doing quarantine?”

And yet with all the restrictions, the Greek gamble seems to be paying off. A month after reopening, coronavirus cases in the country reached a record low while visitor numbers continue to climb — especially from the United States, where airlines like American and United, are offering more direct daily flights to Greece than at any other time.

“I talked to one of my friends right before I came, and he’s like, you’re the fourth person I talked to today who’s going to Greece. What’s going on in Greece?” said Melissa Pappas, a New Yorker visiting the Acropolis with her father and sister. They booked the trip last-minute after learning of the reopening and were exploring Athens before heading north to climb Mount Olympus.

“When Greece opened up May 14, we said, let’s go,” said Alla Wilson, a marketing director from Memphis visiting Greece with her husband of one year. “We got married in May 2020 and had to cancel everything. So, technically, this is our honeymoon and our anniversary trip,” she said.

After arriving in Athens, Ms. Wilson and her husband hiked through northern Greece before heading to the islands, Santorini and Antiparos. “We’re super happy we were able to come when we did,” she said. “It’s the perfect time. It felt totally safe. You avoid the crowds. You don’t have to wait in line.”

‘And now the foreigners are coming’

To be sure, the popular tourist sites were significantly less crowded when I visited than they were a couple of years ago, when a high-season Athens visit was starting to feel like a bad call. I found myself nearly alone at times in the shadow of the Parthenon — that lodestar of Greek antiquity that Le Corbusier, the influential modernist architect, called “the basis for all measurement in art” — something that would have been all but impossible in years past. An Acropolis guard told me that when the site first reopened in April, many Greeks came to visit, often for the first time. “And now the foreigners are coming,” she added. “which makes us very cheerful.”

There may be nowhere in the world that had as drastic a transition from full lockdown to global reopening as did Greece. As late as early May, there was still a 9 p.m. curfew and residents could only leave their homes for a limited number of essential reasons with official government permission through an automated text message system. But only a month later, I went to visit the newly opened restaurant Tzoutzouka in the ex-industrial Rouf neighborhood southwest of Omonia Square and found the terrace full with chicly eccentric Athenians across at least three generations.

“It’s amazing — always a full house,” said the chef Argyro Koutsou. “We had faith that it would be good, but we didn’t expect that it would be so much so soon.” Though she has no formal culinary training, the Athens native gained a cult following while cooking at restaurants on the islands of Zakynthos, Paros and Chios, where she became known for her adventurous cuisine that jumps from region to region, sampling and reinterpreting traditional Greek recipes using ultra-local, unexpected ingredients. “I use things that most people don’t,” she says. “I am a head-to-tail person. I love the wild fish that is not very noble. If it’s fresh and it comes from good water and you treat it with respect, it’s always a tasty dish.”

Highlights at Tzoutzoukas include mashed yellow split peas from the tiny island of Schinousa with pickled calamari and, from the village of Arachova, a fermented mixture of grain and yogurt called trahanas, which is served with smoked mackerel, lemon thyme and mascarpone and spiced with Carolina reaper chili oil. Along with Annie Fine Cooking in the Neos Kosmos neighborhood, Tzoutzoukas is one of several Athens restaurants run by female chefs that opened for the first time during the wider Greek reopening — so far, to great success.

“We were worried that people would be sort of numb, but it was exactly the opposite,” Ms. Koutsou said. “The first days, you would see at the table that the friends who met would not touch. But after three weeks, as vaccinations increase, people are opening up a lot.”

Of course, not everyone is so gung-ho about the reopening — especially after last year, when Greece opened to tourists only to see Covid rip through the country at the end of the summer, flooding the hospitals and leading to stringent lockdowns.

“In June and July the cases were so low that we completely forgot about the virus and then suddenly in August it started going crazy. And we were like, OK, we’re all going to die now,” said Ariadni Adam, a journalist for Vogue Greece. “And I think that if we go about it the same way, September is going to be the new Athenian variant or Greek island variant or whatever. I’m in favor of tourism opening, because I do realize it’s our economy and we need to bounce back, but you still need to monitor the situation.”

I spoke to Ms. Adam at the National Gallery in the Pangrati district, a museum primarily devoted to post-Byzantine Greek Art that opened in March after an eight-year, 60-million-euro (about $71.6 million) expansion, one day before the 200th anniversary of the Greek War of Independence. A temporary exhibition focuses on that period of the country’s history, but I was most entranced by two extraordinary Greek modernist painters: Konstantinos Parthenis, whose dreamlike, post-Impressionist works reinterpret Byzantine and Hellenistic imagery, and his student, Yannis Tsarouchis, who perhaps more than any other came to define Greek modernism with his arresting depictions of sailors, soldiers and other male bodies.

In the coming months, the Greek culture calendar is bursting back into bloom, with outdoor festivals, like the Athens and Epidaurus Festival, featuring a Brian Eno performance on Aug. 4 at the base of the Acropolis, and an Onassis Culture exploration into artificial intelligence, as well as more niche gatherings, like the return in October of the cultish electronic music festival Nature Loves Courage to the shores of Crete.

“Our main goal now is to create content that is not about what we’ve missed but what we long for. Art about the present,” said Afroditi Panagiotakou, the director of Onassis Culture, which is also sponsoring the seventh Athens biennale this fall.

A rush of euphoria

After a few days in Athens, I headed to Piraeus to catch a ferry to the islands, making sure to fill out my form confirming I had recently tested negative or was fully vaccinated (it’s honor system on the ferries). We cast off in the early evening, and I felt my first real rush of post-pandemic travel euphoria as I watched the sunset glint golden over the Aegean Sea from the wind-blown rear deck, where Greeks and foreign visitors filled the tables to eat and drink, smoke and talk late into the evening.

“I’m going to paint and I’m going to make pottery and I’m going to swim and I’m going to eat,” said Carolyn Nichols, a retired cosmetologist and sometimes-artist from Santa Barbara, Calif., sharing a bottle of wine with friends on the deck. She was headed to Amorgos for three weeks, a trip she booked without a second thought when she learned Greece was opening. “I want to travel while I can still walk, talk and find the airplane,” she said.

We stopped at Syros after nightfall, the lights of the port and illuminated hillside church domes glittering over the darkened sea, then continued on to Paros, my final destination. Known for its ancient marble quarries and classic Cycladic hamlets, Paros is a favorite with affluent Europeans, especially the French, whose villas and vacation homes are scattered throughout the island.

Many of them had returned, either by air, by ferry or perhaps by mega-yacht, a segment of Greece’s travel sector that not only weathered the current economic slump, but is thriving beyond all expectations. As I was reminded by Fotis Geranios, a charter manager for the International Yacht Corporation, it bears remembering that for many of the wealthiest people on the planet, the last year and a half has been very good for business.

“Last season was good, not amazing, but this year is crazy,” he said, adding that Americans make up a large part of the increase. “They spent last year in the Bahamas and now they want to return to the Med. The last six months have been busier than ever before.” He had many charters last year where the passengers never got off the boat, Mr. Geranios said. They would dock for supplies and sail on.

But it was another story for the hotels, restaurants and other small businesses across the islands, so many of which depend heavily on an influx of foreign visitors to stay afloat. For them, the reopening is a lifeline.

“It’s like war. It’s crazy. Life is beautiful and then suddenly everything changes,” said Mario Tsachpinis, the 38-year-old president of the restaurant association of Naoussa, Paros’ most picturesque and popular settlement, whose restaurant Mario sits in Naoussa’s elegant old port. It was an extremely difficult time for the restaurants on the island, said Mr. Tsachpinis, whose father opened the traditional ouzo place a few doors down and whose brother owns the taverna next door.

But after months of fear, uncertainty, lockdowns and ever-shifting regulations, the tourists were finally back, clinking glasses of local wine over Mario specialties like sun-dried octopus with spicy lemon jam, and risotto with saffron, fresh vegetables and white fish as the sunset bathed the old harbor dock in rose gold and magenta.

“Two years ago was the best year in decades, so it’s not a good idea to compare to that, but this year is much better than last year,” said Nikos Frantzis, a former financial journalist who runs Bungalows Marina, a simple but tasteful hotel just outside Naoussa, with his wife, the food writer Niki Mitarea. “It‘s better than our expectations,” he added. “So that makes us more optimistic about the future.”

I spent much of my last day on Paros at Kolymbithres, the island’s most remarkable beach, which sits within a vast, shallow bay where giant curved rock formations worn marble-smooth by the passage of time rise from the soft sloping sand to form a string of natural salt pools and secluded coves.

“It’s like a breath of fresh air,” said Orpheus Christopoulos, a tattooed local in swim trunks selling cocktails on the beach when I asked him how he felt about the reopening. “It was a strange winter, a hard winter,” he said. He lost his father to Covid. The lockdown was extreme: “The hardest part was the local fishermen couldn’t even go fishing,” he said.

“Life on the island changed a lot. We miss the music. We miss the Panigiri,” Mr. Christopoulos added, referring to the traditional festivals of music, food and dance that have gone on for centuries in Greek island villages until the pandemic brought them to a halt. It’s still unknown when the Panigiri will return.

But before long, another drink seller ran down to the beach with a portable speaker slung around his shoulder blasting reggaeton, grinning. A nearby group of French sunbathers voiced their approval. A Romanian couple proposed a toast. The music was against the rules. We all knew it, but as the waves lapped the rocks under the white-hot Aegean sun, no one seemed to care.

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