Let's say you weren't supposed to be building a nuclear bomb, but you went ahead and did it anyway. You'd want to test it somewhere without getting caught, somewhere as remote and isolated as exists on the planet. You'd want to be as far away as possible from any people, from any continent, from any fishing ground, from any air corridor or shipping lane or cruise ship itinerary.

You'd want a place like Bouvet Island.

Midway between the bottom of Africa and the Princess Astrid Coast of Antarctica, it's arguably the most solitary piece of real estate on earth, a lonely pimple jutting out of the gray, heaving seas of the South Atlantic. You could journey to the most remote inhabited spot on earth, Tristan da Cunha, and you'd still have another 1,000 miles to go to reach Bouvet Island.

Ninety-three percent of it is covered in glacial ice, the rest in penguin guano. It's an overseas possession of Norway, under the weary supervision of that nation's Polar Department of the Ministry of Justice and Police. Other than dispatching a small and reluctant crew every decade or so to service an automated weather station, Oslo pretty much ignores its forlorn outpost. It would be the perfect spot to explode your nuclear bomb.

Which apparently is what someone did on Sept. 22, 1979. Someone -- possibly South Africa or Israel, possibly Taiwan -- set off a 2- to 3-kiloton nuclear bomb in the waters off Bouvet Island. It might have gone unnoticed, but the telltale double flash was spotted by the unblinking eye of an American spy satellite, and the radiation was detected by Australian scientists in Antarctica. The official position of the U.S. State Department is that it never happened, but most scientists believe this is a political cover-up.

The fact that news of this probably has never reached you attests to what an impossibly distant and godforsaken place Bouvet Island is. Only a few dozen humans have ever left their footprints on it, and it's a safe bet most of them would happily have passed on the honor.

But there is a small and obsessive group of people scheming, plotting, cajoling and ultimately trying to buy their way there. They are known as country collectors, and they spend their lifetimes journeying to the farthest and most obscure reaches of the globe, from Abkhazia to Umm Al Qaiwain, filling their passports with rare and exotic stamps. Bouvet Island is to them what Everest is to peak baggers, what the British Guiana 1c magenta is to philatelists, what the Apple Tree Girl 141X is to collectors of Hummel figurines.

Only a tiny handful of country collectors -- precisely eight by one estimate, "not quite 20" by another -- have ever managed to cross Bouvet off their lists. The most recent is a 40-year-old dot-com millionaire from San Francisco, Charles Veley, and he believes this, along with all his other peregrinations, qualifies him as the most well-traveled person in the history of the world.

Veley has certainly seen more of the globe -- far, far more -- than Captain Cook, Magellan or Marco Polo. He has been to Meghalaya, to Mizoram, to Molukkas, methodically crossing each place off his long list. He has been to the Kermadec Islands, to Kingman Reef, to Kwazulu-Natal, filling six passports with obscure stamps and visas. He has been to Lampedusa, to Lord Howe Island, to Limpopo, missing his daughter's first steps and first birthday party. He has been to Ras Al Khaimah, to Rotuma, to Rio Muni, spending a million and a half of his own dollars on airplane tickets, freighter passages and sailboat charters.

Tatarstan, Chuuk, the Daito Islands, Chuvashia: If you can name it -- and, especially, if you can't -- Veley has probably been there. He has, by his own count, set foot in 518 different countries, territories and islands, which he believes puts him far ahead of any other country collector. And while most of his rivals have filled their passports over a lifetime of travel -- many are in their 70s and 80s -- Veley has done it all in just five years.

"If you want to have a complete world view you have to go everywhere," he says. "Five hundred countries is better than 400. Every place you learn something new."

Relaxing in the Pacific Heights home he shares with his wife, Kimberly, and their 2-year-old daughter, Catherine, he has just unpacked his bag after a swing through 16 of Russia's 21 autonomous provinces. "If I had another week I could have gotten the rest," he says. "But I promised Kimberly I'd be home." Dressed in a Christmas Island T-shirt and warmup pants, Veley is boyish and enthusiastic -- which is quite remarkable, considering that he has got more miles on him than a 1962 Volvo.

Veley's house has none of the tchochkes you typically see in a traveler's home: no carved African masks, no Balinese puppets, no Tibetan prayer wheels, no wall map porcupined with colored pins. "I'm not much of a souvenir guy," he says. "I've been traveling nearly full time, and that's a lot of stuff to lug around with you."

His claim of being the world's most traveled person seems pretty unassailable -- except that there's another guy in the Bay Area who asserts that he, not Veley, is the world's most traveled person. Jeff Shea, 50, owns a manufacturing company in Richmond and has not only visited all but three places on the most commonly used world list, but has also reached the summit of the highest mountain on every continent, including Everest. He has walked across Transylvania, sailed across the Pacific Ocean and spent 39 days floating down a river in Papua New Guinea on a raft held together by jungle vines.

"Charles is a nice guy, but his claim is bogus," Shea says. "I've seen a lot more of the world than he has, hands down. I am the world's most traveled person."

Responds Veley: "Jeff is a very nice guy, and he's done some really interesting things. But he hasn't been to as many places as I have."

Nobody is disputing anyone else's travel claims. The argument is over how you define the rules of the game: how you decide what a separate "place" is, and how you define what a "visit" is. But one thing seems clear: the gloves are coming off in what up to now had been the rather genteel world of country collecting.

If there is such thing as a wanderlust gene, it must be recessive. Neither of Veley's parents liked to travel. But almost from birth he was overcome by the urge to roam. Not long after he took his first wobbly steps, his parents would find the kitchen door of their Brooklyn home open and their young son gone. He'd toddle several blocks before a neighbor brought him home. When he was 6 he'd wander out to the garage, climb into the family Land Rover, prop open the Rand McNally North American Road Atlas on the seat next to him and undertake imaginary road trips out to California and back, his hands on the steering wheel, his feet a long way from reaching the pedals.

Veley started young for a serious country collector, and he started with advantages his competitors can only envy: He's got all the time in the world, and he's rich. In 1999, at the height of the dot-com boom, the high-tech company he and three friends started, MicroStrategy, Inc., went public. Overnight, Veley was a millionaire many, many times over. He was just 35.

Burned out on 100-hour workweeks, he took a sabbatical and set off on a year-long honeymoon abroad with Kimberly. They lived in Paris for three months and Munich for another three, and then struck off for Fiji, New Zealand, Bali, Bhutan, India, Australia and Egypt. Having too much fun to go home, they re-upped for another year on the road.

Somewhere over the Sea of Japan, while flipping through an in-flight magazine, Veley came across an article about the Los Angeles-based Travelers' Century Club, an exclusive society for people who've visited at least 100 countries. "I thought we were really elite travelers because we'd been to 65," he says. "But this fired my competitive juices."

The couple held nonstop tickets from Osaka to Hong Kong, but Veley discovered they could change the routing and fly via Okinawa and Taiwan, which were both on the TCC list of countries. He switched their tickets and they spent all of four hours in each place -- but it was enough to cross them off the list. A country collector was born.

It took him only a couple of months to reach no. 100 (Jersey Island). He hit no. 200 the following year (Sikkim), and no. 300 less than a year after that (Chad). Collecting countries became Veley's full-time job. The most he has spent on a single trip is $25,000, but that turned out to be a bargain. He flew to the South Pole, where he could stand in one spot and touch six "countries" at the same time: the Argentine, Australian, British, Chilean, French, New Zealand and Norwegian Antarctic claims, which all meet at the South Pole like slices of a pie.

Kimberly accompanied him for the first couple of years -- she now has more than 200 countries under her belt -- but dropped out when Catherine was born in 2003. A second child, a son, is due in October.

Even though Veley is 54 countries short of completing his own list, he's about to call it quits now. "I did as much as I could, and now I'm done. At some point you have to declare victory and move on."

Now Veley is working hard to raise his profile and get himself widely recognized as the world's most traveled person -- his Web site proclaims him "the #1 ranked traveler on earth" -- and this clearly rankles some of his competitors.

John Clouse, an 80-year-old practicing attorney from Evansville, Indiana, was listed in the Guinness Book of World Records as the world's ultimate traveler for a decade. It cost him, among other things, six marriages, and he doesn't like the idea of giving up his title.

"It's a competitive sport now," he says. "Charles gets off the plane, bops around and gets back on. I don't mean to sound mean-spirited -- he's been very kind to me -- but he wants me to surrender my sword."

So is Veley the world's most traveled person or not?

It all comes down to whether you consider an ice-covered rock in the middle of the South Atlantic a country. Or whether the Cook Islands are one island group or two. Or whether Mustang is a unique and distinct place, rather than just another region of Nepal.

Deciding what is and what isn't a separate "country" can keep collectors arguing halfway to Bashkortostan. There are generally accepted to be 193 sovereign nations in the world -- the 191 members of the United Nations, plus Taiwan and the Vatican. But consider, for example, Tahiti: It is fully a part of France, yet most would say it is a separate place. If you've been to Tahiti you haven't really been to France, and vice versa. Once you start down this road it just becomes a matter of how finely you want to parse things. For the purpose of collecting you start with those 193 sovereign nations and begin adding their overseas possessions, colonies, territories, autonomous regions, protectorates, trusteeships, enclaves, mandates, geographically separate island groups and all the world's other "discrete geographical, ethnological or political entities." To keep the nomenclature simple, many collectors call each of these places a "country."

No one can agree on the total. The Travelers' Century Club has 315 "countries" on its list. The American Radio Relay League, a group that competes to make radio contact with the most places, counts 335. Veley lists 572 on his Web site, www.mosttraveledman.com, which he's hoping to establish as the final arbiter. Shea is preparing to unveil his own list, based on International Standards Organization definitions, that stretches to 3,996 different places.

It's safe to say that Veley's list includes a lot of places he's been and Shea hasn't, and vice versa.

Deciding what constitutes a "visit" is also contentious. Under the TCC rules, if your flight from Cape Town to Heathrow makes a brief refueling stop at Entebbe, you can cross Uganda off your list. Veley is championing more vigorous standards: You have to get your passport stamped, or, if that's not possible, come back with firm proof: a photo, an airline ticket or a credit card receipt. This has forced him to venture into Iraq twice. The first time he walked out to the middle of a bridge over the Tigris River on the border between Turkey and Iraq and simultaneously pantomimed "Don't shoot!" and "I just want to dab my foot over the line." He's since flown into Baghdad to get his passport stamped.

But is this really what most people would consider travel? Veley's astounding harvest of 518 countries in five years works out to an average of 3.5 days per country. Factor in travel time and the occasional stop back in San Francisco, and there isn't a whole lot of time to get to know these places.

"It's nothing more than stepping off an airplane and getting right back on," says Shea. "In my book, that's not travel. The only people who might be impressed by something like this is people who haven't traveled much."

Responds Veley: "Who's to say how long is long enough? If you stay in a place for a week, they'll tell you you really need three weeks to get to know it. If you stay three weeks they'll say you need to spend the whole season. You can never win that game."

"It's all about bragging rights," says Klaus Billep, chairman of the Travelers' Century Club.

Get any two hard-core travelers together, and you'll witness a not-so-subtle game of one-upmanship: "Well, sure, everyone treks to Everest base camp," one will say. "I trekked to K2 base camp. It's a lot harder. Hardly anyone does it, you know." Announce that you climbed the Great Pyramid to watch the sunrise, and the next guy will say he did it, too -- with a blind Egyptian soothsayer. Trot out your tale of coming face to face with a grizzly bear in Alaska's Gates of the Arctic National Park, and someone else will trump you with a yarn about being stalked by a polar bear.

The eyes of nontravelers quickly glaze over when these stories start flying, which is why extreme travelers tend to associate with like-minded people in clubs like the TCC. Today it has 1,900 frightfully well-traveled members around the world and chapters in eight U.S. cities, including San Francisco. When they aren't trotting the globe, they meet for regular luncheons to swap travel tales and exchange tips on getting to the Ryukyu Islands or Srpska. Sometimes they pool resources to charter a boat to some far-flung island group or accompany one another on the tedious border crossing between Burkino Faso and Togo. Up until recently the competition, such as it is, has been low-key and gentlemanly. Even Veley and Shea once teamed up on an expedition to the British Indian Ocean Territory.

"It's a friendly group, and we help each other out whenever we can," says Bill Altaffer, 62, a retired history teacher and ski instructor from Mammoth who's been to 470 "countries." "We all want to see as much of the world as we can. I can't look through a magazine and see a picture of an interesting place and not want to go there. Just hearing the word 'Timbuktu' makes me want to go."

There's a fuzzy line between methodically ticking countries off your list and full-on obsession. Dromomania, the obsessive urge to travel, is a recognized psychological affliction listed in the Diagnostic and Statistical Manual of Mental Disorders. Sufferers of what's also called "the vagabond neurosis" will "spend beyond their means, sacrifice jobs, lovers and security in their lust for new experiences."

"They become involved in the minutia of travel, buying the tickets, packing their bags and planning where to go," Dr. Joan Lakin- Marantz, a New York psychotherapist, told the Toronto Globe and Mail. "It's distraction against the pain of loneliness."

Early in the 20th century, according to the newspaper, a group of French psychologists and psychiatrists took note of Jesus' frequent wanderings from Nazareth and concluded that he probably suffered from dromomania.

To a person, country collectors deny they're afflicted with any sort of mental disorder. "It's just a collectors' mentality," Veley says. "When I was collecting baseball cards, I just had to have the whole set. But I was never the kind of kid to just go out and buy the set. I'd buy individual packs, trade with my friends and flip cards until I finally had them all. It was the challenge. The journey is always more important than the destination."

So is Veley the most traveled man in the history of the world or not?

"It's very much up in the air," says Clouse, the past record-holder. "I don't think he is."

Nor is Shea willing to concede. His travel resume is awfully impressive: Not only did he climb Everest, he did it by a harder route than most summiteers use. He traveled overland from Bangladesh to Egypt -- through Iran and Iraq, among other places -- and spent five months knocking around Africa. Along the way he's contracted two strains of malaria, been jailed in Jordan and watched a man die by falling into molten lava in Hawaii. His daughter, Lani, is in the Guinness Book as the youngest ever to visit all seven continents: two years, 307 days.

Shea has ticked off 317 countries on the TCC list and 1,246 of the places on his own 3,996-place list. This list, he says, is based on provinces rather than countries, and is a better measuring stick for extreme travelers. With the other lists, "you could spend an hour at the airport in Beijing and say you've been to China," he says. But under Shea's system, you'd have to visit each of China's 23 provinces, five autonomous regions, four centrally administrative municipalities and two special administrative regions. "Charles' list has a lot of rocks out in the middle of nowhere in the ocean," he says. "I'm more interested in the living space of the human race."

It wasn't until Veley publicly anointed himself as the world's most traveled person that things became strained between the two. "It's declaring yourself the champion by your own criteria," Shea says, "when no one else is playing that game."

Shea says he did more than just tag a country and cross it off his list. "I tried to get out and see the place, to go overland if possible. A list is just a list. It has nothing to do with how in-depth you see a place."

Veley retorts that Shea has a number of touch-and-go visits on his resume (which Shea doesn't deny.) And, for the record, Veley can hold his own when hard-core travelers start swapping yarns. There's the time he spent a couple of days on Pitcairn Island, bunking with the great-great-great grandson of HMS Bounty mutineer Christian Fletcher. "He's got a whole closet full of country and western CDs," Veley says. "Everyone on Pitcairn is crazy for country and western. The only station their radio could pick up was out of Sacramento, and it was all country and western."

Then there's the time he had to spend the night in no-man's land between Russia and Georgia, temporarily a man without a country. And the time he got hopelessly lost in Kabul and spent hours riding around the city in a taxi, steering around bomb craters while searching in vain for his guesthouse. He's had Kalashnikovs pointed at him in West Africa by teenagers liquored up on banana beer and had to bribe his way into Chechnya, and back out. His voyage to Bouvet Island and back turned into a 71-day epic that included two weeks stuck in pack ice.

But one place has so far remained frustratingly out of Veley's reach, and Shea's, too. It has proven to be far more elusive than Mpumalanga or the Tokelau Islands: It's the Guinness Book of World Records. Guinness listed the record for "World's Most Traveled Person" until 2001 -- Clouse held it -- but finally threw up its hands and dropped it from the book. No one could agree on a standard, says spokesman Sam Knights.

"The difficulty," he wrote in an e-mail, "is that no single list is any more valid than any other, and inevitably each proposed list suits a particular proposer." Choosing one person's list, he says, would put his rivals at a big disadvantage.

"This probably sounds like an overreaction, but there is a core of around four or five people who seem to do little else but travel, and each is extremely competitive and determined."

Last year Veley got Guinness to agree to give him the record if the Travelers' Century Club would validate the claim, but after initially agreeing to do so the club thought better of it and backed out. "It's on an honor system," says Billep, the club's chairman. "It's so hard to prove. So we decided to stay out of it." For the record, though, Billep says Veley is "absolutely the most widely traveled man in history."

Shea and Clouse would disagree. But, then again, Veley's been to Bouvet Island and they haven't.

Charlie's Bottom 10 (a few low points along the way)

10. Tortuguero, Costa Rica: Tree frog hops onto Charles' forehead, promptly urinates.

9. Ushuaia, Argentina: Peter I Island expedition cancelled following 26-hour transit from SF; next day, Charles is mugged in Buenos Aires, watch stolen.

8. Stanley, Falkland Islands: HMH Chief Surgeon treats Charles's hemorrhoids with 10-inch needle.

7. Alice Springs, Australia: Charles is denied entrance to dusty Outback nightspot for failure to meet dress code!

6. Near Livingstone, Zambia: Sudden storm overturns Charles and Kimberly's canoe in Zambezi river among hippos and elephants, 1 mile from nearest house.

5. Suva, Fiji: 73-year-old Danish man sails off with $3,000 deposit after freak gales cancel expedition; claims "Act of God."

4. Hazyview, South Africa: Exotic spices cause allergic reaction. Charles' face swells to unrecognizeable dimensions while wild animals lurk outside.

3. Christmas Island, Kiribati: Skipper for upcoming 1,000-mile-charter voyage arrives 3 days late -- drunk, stoned and fondling himself.

2. San Jose, Costa Rica: During endoscopy on Charles, Kimberly passes out. Doctors treat Kimberly on floor while Charles sits intubated on table.

1. Sint Maarten, Dutch Antilles: Starving and cash-poor Charles questions 1:1 Euro/Dollar exchange rate at crummy airport snack bar. Shopwoman vigirously defends rate, retorting "You should travel more!"