Last summer, my Royal Air Maroc flight from Casablanca landed at Malabo International Airport in Equatorial Guinea, and I completed a 50-year mission: I had officially, and legally, visited every recognized country on earth.

This means 196 countries: the 193 members of the United Nations, plus Taiwan, Vatican City, and Kosovo, which are not members but are, to varying degrees, recognized as independent countries by other international actors.

In five decades of traveling, I’ve crossed countries by rickshaw, pedicab, bus, car, minivan, and bush taxi; a handful by train (Italy, Switzerland, Moldova, Belarus, Ukraine, Romania, and Greece); two by riverboat (Gabon and Germany); Norway by coastal steamer; Gambia and the Amazonian parts of Peru and Ecuador by motorized canoe; and half of Burma by motor scooter. I rode completely around Jamaica on a motorcycle and Nauru on a bicycle. I’ve also crossed three small countries on foot (Vatican City, San Marino, and Liechtenstein), and parts of others by horse, camel, elephant, llama, and donkey. I confess that I have not visited every one of the 7,107 islands in the Philippine archipelago or most of the more than 17,000 islands constituting Indonesia, but I’ve made my share of risky voyages on the rickety inter-island rustbuckets you read about in the back pages of the Times under headlines like “Ship Sinks in Sulu Sea, 400 Presumed Lost.”

I’ve had hundreds of adventures inside these countries, but for certain countries, the adventure started before I could even get in. The difficulties I encountered trying to get tourist visas taught me, in their own way, about places I had yet to visit and their relationship with the wider world. (Getting a visa to famously isolated North Korea is actually not that difficult: The United States does not bar its citizens from going there, and the North Korean government, though it despises America, loves Americans’ money and is happy to provide visas—albeit exclusively through expensive, government-approved tours.) Here are the nine countries for which I had the hardest time obtaining visas.

* * *

Saudi Arabia was truly tough. I tried, from 2000 to 2009, without success, or even explanation for my failure, to secure a tourist visa to the Desert Kingdom—though at the time the Saudi Commission for Tourism and Antiquities had no history of granting tourist visas to non-Muslims. Because I had to get in to complete my quest, I worried that I might have to convert to Islam, memorize the Koran, study with a mullah, attend a mosque, and forget I was an ultra-liberal Jewish atheist.

This became especially frustrating in 2011, when I was in Bahrain, a quick drive over the King Fahd Causeway to Saudi Arabia. After I failed yet again to get a visa, an unusually candid Saudi consular officer finally told me why. He said, in essence: “Look, we have lots of oil money, so we don’t need your few tourist dollars. We have 2 million Muslim pilgrims visiting every year to do the Hajj”—the annual pilgrimage to the holy city of Mecca—“and they are no trouble. Some of our conservative citizens do not want non-Islamic Westerners coming and stirring up our people with liberal ideas. And we certainly do not need the bad publicity if you are hurt or killed in our country by some radical.”

Finally, I found a well-connected tour agency in Michigan that arranged for me to reach Saudi soil disguised as part of a team studying under the guidance of an archaeology professor and expert on the tiny clay counters used for keeping financial accounts in the Middle East some 7,000 years ago. My own finances were $9,000 weaker after airfare and tour arrangements.

Kiribati was too small and poor, when I first applied for a visa in 2006, to afford an embassy in the United States. It had, instead, created eight “honorary consulates” scattered around the world, and I was directed to a consul in Honolulu who usually was out surfing. I eventually acquired my visa from the consul in Fiji while en route to other South Pacific nations. The situation is much easier today: For several years, Kiribati has not required tourist visas from U.S. citizens staying less than a month.

Chad required, and still requires, the visa applicant to submit a letter from a sponsor or hotel in the country’s capital, N’Djamena, inviting him or her to visit, and setting forth the relationship and the purpose of the trip. When I went in 2012, only two or three hotels there were issuing such a letter, and in order to obtain it, I had to book, and pay in advance for, a room at a nonrefundable $300 a night.

The entry problems are not over after booking, however.

Right after I arrived at the N’Djamena airport, a uniformed officer rubbed his thumb and fingers together as I approached and said, “Money, money, money.” He asked for a bribe of $50 to let me leave the airport.

I told him, in my most forceful French, that I had already paid for my visa.

He looked unimpressed: “Money, money, money.”

I lied and told him that the Chadian ambassador to the United States had assured me that I did not have to pay more money to enter Chad.

He looked at me as if I were a simpleton: “Money. Money.”

I asked him to show me the regulation that required me to pay.

He looked at me as if I were a troublemaker.

I told him I would pay him only if he gave me a signed receipt.

He choked with laughter and shared the joke with two of his colleagues, who were waiting for their cut.

As the end of both his shift and my patience approached, the price of the bribe dropped to $15.

I had only a twenty, which I gave him, and asked for change. For this I got the biggest laugh of the day and a wave to get the hell out.

Nauru was, for me, from 2001 to 2007, impossible to get a visa to.

From the late 1960s through the early ’70s, the denizens of this tiny Pacific island were the wealthiest people on the planet per capita, due to the dense and valuable guano deposits left on the island by fish-eating seabirds over a period of eons. The last of these rich phosphate resources were depleted by 2006, and the suddenly impoverished Nauruans were compelled to make a living in other ways. First the country became a tax haven and alleged money-laundering hub for Russian criminals. Then it established internment camps for refugees as part of “the Pacific Solution” to prevent the refugees from reaching or remaining in Australia, and effectively closed its borders to all visa-seekers not approved by the Australian High Commissioner to prevent foreigners from monitoring the migrants’ conditions.

Nauru relaxed these restrictions with the formal end of the Pacific Solution in 2008. And though the country remains a dumping ground for many refuge-seekers, it is now focused on legitimate enterprises, including tourism, making it far easier to get a visa—the island’s airline arranged mine, and I finally visited in 2011. But unless you are on a crazy quest to visit every country, you might want to skip this uninviting strip-mined mess of a speck of limestone.

Russia wouldn’t have made this list but for my fourth visit there in 2010, when I discovered the liability of being an American seeking to enter Putin’s land: While most of the rest of the world’s peoples can apply for a visa to Russia using a simple single-page form of 21 questions, U.S. citizens must use an arduous “new form implemented on the basis of reciprocity” that has 41 often-intrusive questions. These include: itinerary details; the name of the person or organization paying for the trip; the names of every country the applicant has visited in the past 10 years (99 for me); the applicant’s current and two previous places of work; every educational institution the applicant has attended; all the professional, civil, and charity organizations of which the applicant is a member or with which he has “cooperated”; the names of all the applicant’s relatives in Russia; the details of any training in firearms, explosives, nuclear weapons, and “biological and chemical substances” (which arguably would include everything from acidophilus yogurt to Drano); and details of the applicant’s military service, including rank and occupation.

To avoid the penalty of immediate rejection for failing to answer every question, and even though I believed the last was none of the Kremlin’s business, I dutifully recorded on the form that, when in the armed services of my country, I had proudly and patriotically helped write and edit the official U.S. Army manual on the construction and location of latrines. (Unfortunately, and despite my good intentions, that left me no room to add that I had later been promoted to sergeant, received a top-secret clearance, and became the crew chief of an atomic cannon.)

Somalia has been devastated by decades of war and terrorism, so it certainly needs tourist dollars, but its government is reluctant to see visitors get killed or kidnapped. A few hotels and guesthouses are, however, open for business, although they primarily cater to diplomats and nongovernmental organizations, and they do take care of procuring visas. They can also book at least four, and preferably six, armed guards who will form a complete perimeter defense around you, with their chief beside you, usually scanning the rooftops with binoculars for snipers. This armed crew, together with two bullet-resistant SUVs in constant contact by walkie-talkie, set me back $750 a day when I visited in 2012. The cost has since risen to $1,350 a day, with little room to bargain. The security team is virtually required for getting a visa, since the government will not let you in unless it is comfortable that you will be protected. I can only guess whether the steep rise in price recently is the result of increased visitor activity or increased danger.

Though my guards bustled me about rapidly to keep me from becoming a sitting target for kidnappers, they did take me for an hour’s walk on the Lido, one of the most beautiful strands of fine-grained, wave-washed white sand I’ve ever seen, lined by formerly luxurious villas, not one of which had retained four intact walls or glass in their windows.

Sudan was a hard nut to crack. From 2004 to 2007, whenever I asked the Sudanese Embassy in Washington about the status of my application, I got the same terse reply: “It is being considered in Khartoum.”

The government in Khartoum is secretive and paranoid. It has sponsored a genocide against non-Arabs that has killed hundreds of thousands in the Darfur region since 2003, and some of its top leaders, including the president, are wanted by the International Criminal Court. It seems clear why they would be reluctant to have camera-toting tourists running around the country, and they severely restrict the number of visitors, where they can go, and what kind of photos they can take.

I finally gave up on the official procedure and found a way in (with camera) thanks to a friend at the United Nations, who put me in touch with an official of the Arab League, who put me in touch with a shady character who “facilitated” my entry in 2008 by crossing several palms with silver to procure a visa.

Yemen was too hot to handle for a long time. After being thwarted for several years in obtaining a visa following the turmoil of the Arab Spring and the resignation in November 2011 of the dictatorial former president, Ali Abdullah Saleh, I was able to snag a visa and enter legally during a rare window of relative peace in January of 2014. But with the overthrow of the government by Houthi insurgents at the end of this January, that window is firmly closed and locked for the time being.

Angola was the most difficult of all the countries I visited. Its stingy visa policy perhaps reflected a widely held belief that foreign visitors only want to steal the country’s diamonds. Furthermore, Angola’s government granted Americans almost no tourist visas for years because of American support for Angolan rebels in a 27-year civil war that began in 1975 and killed more than half a million people. No one I knew had been granted a visa during the years I tried to get one, between 2004 and 2008.

I was finally able to enter the country in December 2012 through a newly formed connection with a highly placed Angolan executive who was able to pull some strings at the Foreign Ministry.

There was not much to see in Luanda except massive traffic jams and high-rise yellow cranes, because the nation was in the midst of an oil-fueled construction frenzy. The countryside I traversed had little natural beauty, and most of the wild animals had been killed during the civil war; the souvenirs were five times as expensive as similar items in other countries; the Portuguese-influenced food was bland and boring; and when I asked for a doggie bag to take my leftovers back to my hotel, I got charged five dollars for the bag.

Angola was the last country on earth that I hadn’t visited at all. (It would take me two more years to visit every country legally—I had sneaked into Yemen and Equatorial Guinea before returning in 2014 with the necessary paperwork to make it official.) It was far from my favorite, but like every other place on the list—from Nauru with its ravaged limestone to Somalia with its machine-gun nests ringing Mogadishu—it was a necessary step on a journey all the way around the world.