TEHRAN — For all of Iran’s attractions — breathtaking scenery and numerous World Heritage sites, among other things — there are plenty of downsides to vacationing in the Islamic republic. Alcohol is forbidden. There is very little night life, at least in public. All women, including visiting foreigners, are obliged to wear a head scarf.

Then there are Iran’s politics: its strident anti-Western stance; seemingly random arrests of people with dual citizenship; hundreds of executions every year; and a rather loose definition of human rights.

None of that has changed, but suddenly Iran is a booming destination for Europeans seeking an adventurous vacation, particularly people from Spain, France and Scandinavia. Even tourism from the United States is picking up, industry insiders say.

“I only knew Iran through the image the government presents in the media,” said Magali Magnim, a 33-year-old video technician from Lyon, France. She and two friends were in Isfahan, one of Iran’s most historic cities, as part of a three-week tour. “But everything is so different from what I expected.”

What surprised her was that it felt safe. “Here on the streets, I feel more safe here than in France,” Ms. Magnim said. “I feel everybody I meet can be trusted.”

The Grand Bazaar in Tehran in July. Credit Atta Kenare/Agence France-Presse — Getty Images

For many tourists, a trip to Iran was always more than just a holiday. It was a journey into the unknown, with a frisson of danger added. For decades, news coverage of the country was overwhelmingly negative, led by such topics as the Islamic Revolution in 1979 and the ensuing hostage crisis; the death sentence issued against the British writer Salman Rushdie; the crackdown on protests in 2009; and accusations that its leaders were trying to build a nuclear weapon. For outsiders, Iran has been a dark and scary place.

What was often lost was the other side of Iran: its ancient history, its young and open-minded population, its food and culture. After the 2015 nuclear agreement between Iran and six world powers, which led to the lifting of most sanctions and a reconnection to the world, the sharpest edges seem to have been taken off. Long suspicious of foreigners, Iranian officials — led by the avuncular-looking President Hassan Rouhani — are now welcoming them.

The number of Western tourists who are visiting is hard to gauge accurately. Officials say more than 5.2 million tourists visited last year, and more are expected this year. But that counts the millions of Shiite pilgrims who come to the country annually.

In comparison, Turkey, the region’s tourism powerhouse, used to receive around 20 million tourists a year before an increase in terrorist attacks, a dispute with Moscow over a downed fighter plane and a failed coup attempt cut into the total.

“In our travel agency, we catered to a thousand Westerners last year and will have well over 2,000 Western visitors this year,” said Hossein Ramtin at the Marco Polo Iran Touring Company, one of the largest tour operators in Iran.

He noted that many visitors are brought to Iran by foreign tour operators and other companies — including The New York Times, which offers cultural tours — and that he expected their numbers to rise. “Especially French and Spanish tourists are coming in large numbers,” he said.

A food court in a shopping mall in Isfahan, Iran, in 2014. Credit John Moore/Getty Images

Opening the country to tourists is part of Mr. Rouhani’s carefully planned outreach to the West, aimed at cementing ties after the nuclear deal. Iran’s culture of hospitality should play a part in that policy, he said during a tourism conference in September, the Iranian news media reported.

Iranian visa policies were already quite simple, with Europeans able to obtain one on arrival. After the nuclear deal was reached, the government extended the tourist visa to three months from two weeks. Americans and Britons are treated differently, permitted to travel the country only in guided tours where they can be watched.

The policy of opening up to foreign tourists is propelling more visits, said Mr. Ramtin, the tour operator. “When they come home, they tell others Iran is safe and secure, and more will come. All in all, our image is slowly being upgraded.”

Every breakthrough in tourism is widely celebrated. Last month, when the Dutch carrier KLM became the latest European airline to fly to Iran, Iranian firefighters sprayed arcs of water over one of its aircraft in greeting. Iranian photojournalists covered it as if they were shooting a red-carpet event. “KLM returns to Iran,” front pages said the next day.

Hotel development, in the deep freeze in the decades of isolation, has kicked in, with three new properties in Tehran since 2015 and more planned. However, overall tourist services are poor in many parts of the country, guides complain.

Basically everything in the industry needs improving, said Pegah Ghanaat, a tour guide who works with Spanish visitors. “The entire tourism infrastructure needs an overhaul,” she said. “It’s as simple as that.”

Visitors aboard a tourist train in Tehran, the Iranian capital, in January. Credit Atta Kenare/Agence France-Presse — Getty Images

Ms. Magnim, the French tourist, and her friends have found a way around the problem of hotel room shortages by using social media as their guide. Through a website called Couchsurfing, they spend their nights in the houses of Iranians who want to meet foreigners.

“When you stay in people’s homes, you get to know the real culture,” Ms. Magnim said. “It turns out many Iranians have the same dreams and ideas we have.”

The number of Iranians offering beds and couches to crash on has mushroomed in recent years, to more than 36,000 from virtually nothing, the Couchsurfing website reports. No money is exchanged, just experiences.

“It’s a great way of showing the real Iran to foreigners,” said Reza Memarsadeghi, 43, who studied philosophy in Vancouver, British Columbia, and returned to Iran to take care of his ailing father. Back in Tehran, he heard of Couchsurfing, and now, six years later, he is known as the Godfather of Couchsurfing, having hosted more than 1,000 foreigners in his parents’ basement. “I’ve stopped counting, to be honest.”

His enthusiasm also showed the limits of how much hospitality Iran’s rulers want their citizens to show. Mixing with foreigners is already suspicious, to Iran’s hard-liners at least, but having hundreds sleep over is too much even for those seeking better ties with the West.

In August, Mr. Memarsadeghi was arrested and charged with making “propaganda against the Islamic republic” for hosting Western men and unveiled Western women who were mingling. “Now my mother won’t let me have guests staying over,” he said.

He was released and is awaiting trial. Still, he wishes that even more foreigners would come to Iran. “It’s all about people meeting people,” he said. “That will change the world.”

Editors’ Note: November 8, 2016
An earlier version of this article failed to acknowledge that The New York Times is one of the foreign companies offering cultural tours of Iran.