Some travelers collect nations the way other people collect stamps, and apparently leading the way are two members of an organization of nation collectors called the Travelers' Century Club.

Parke G. Thompson, a 68-year-old lawyer from Akron, Ohio, has visited 304 of the 308 countries on the club's official list, and in the 1987 "Guinness Book of World Records" he has been dubbed "the most traveled living American." However, lawyer John D. Clouse, 62, of Evansville, Ind. recently matched Thompson's total.

The Travelers' Century Club, open to modern-day explorers who have set foot in at least 100 countries, currently has about 1,000 members. One of the youngest is Clouse's 7-year-old son Chauncey, whose total is 128.

Thompson and Clouse made it on their own to most of the places they have visited, but increasingly tour operators are putting together packages to satisfy today's Marco Polos seeking out the remote corners of the world. Among those coming up in the next few months is a guided trip to the South Pole offered by Society Expeditions. Even Thompson has his eye on that one.

The South Pole adventure would take Thompson to four separate territories in Antarctica, which just happen to be the last four places he needs to complete his Travelers' Century Club list. However, he is temporarily stumped by Society Expeditions' $35,000-per-person asking price and is looking for a sponsor. For the dedicated collector, remote lands can be as expensive as rare stamps.

Clouse still lacks Albania, a Balkan nation that does not admit American tourists; Wake Island and Midway Island in the Pacific; and the British Indian Ocean Territory in the Indian Ocean. He began traveling "for fun" in 1958, he says, "but about nine or 10 years ago I got the idea I might get to visit every country in the world."

The collector's bug had hit him hard. "Since then I've been transfixed."

Clouse regularly schedules six or eight foreign trips a year to add new destinations. Thompson tends to take one long, annual getaway of six to eight weeks to explore a region of the world. Both obviously seek out new places rather than returning regularly to a favorite vacation spot. Says Thompson in what may be the nation-collector's credo: "I'd rather see a little of a lot than a lot of a little."

As the maximum number of countries, 308 is somewhat arbitrary, which the club readily acknowledges. The United Nations has enrolled only 159 nations to date, but they are all full-fledged countries. The club, on the other hand, lists many places that, it says, "are not actually countries in their own right."

These places -- among them distant territories, islands and states -- have been included, explains a membership brochure, because "they are removed from parent countries, either geographically or ethnologically." For example, Alaska and Hawaii are each listed separately from the United States. For a nation collector, that's a total of three points in the climb to 308. A sweep through Yugoslavia can earn you six as you visit the former Balkan kingdoms that now comprise the country.

Also, "visit" is a term that the club, out of some necessity, has had to treat rather loosely. "After consideration as to how long one must have stayed in a country or island group to qualify," the brochure says, "it was decided that even the shortest visits would suffice -- even if only a port-of-call or plane fuel stop."

Thompson likes to explore in depth the countries he collects, but he has had to resort on occasion to a visit as defined by the club. His problem, like Clouse's, was how to add unwelcoming Albania to his collection.

His solution: "I scheduled a flight from Rome to Bucharest that stopped at the airport in Albania." Clouse says he's trying this year to book a seat on a similar flight.

Getting to some of the world's remote spots, or those where the government frowns on tourists, has required ingenuity and persistence. Saudi Arabia, while admitting American business travelers, generally bans U.S. tourists. "Getting into Saudi Arabia was an uphill battle all the way," says Thompson.

For two years, he called the secretary in the visa office every third month attempting to build a rapport. "Her answer was always the same -- 'No.' Then one day she mentioned to me an 'in-transit' visa." Much as he had done to get to Albania, he booked a flight itinerary from Egypt to Ethiopia that included an overnight stop in Saudi Arabia -- and was granted an in-transit visa for the short stay.

Both Thompson and Clouse have had to stay in primitive accommodations at times, but as Thompson puts it, "When you're bound and determined to walk on water, you don't really classify this as a problem." Thompson says he almost always travels without advance lodging reservations. "You've got enough pressure just trying to make air schedules."

Neither has any intention of slowing down when they have collected their last destination. Thompson is looking forward to "motoring around Europe." Clouse wants to take the train across Siberia in the Soviet Union.

The Travelers' Century Club, which was founded in 1954, charges a $100 per person initiation fee. Yearly dues are $15. Aspiring members who have not yet reached the 100-nation minimum for membership can receive the organization's membership newsletter for $15 a year. For information or an application: Travelers' Century Club, 8033 Sunset Blvd., Box 9, Los Angeles, Calif. 90046.

Among the escorted tours that may help you collect some of the more remote or less frequently visited places in the world:

South Pole: Society Expeditions bills its Nov. 18 trip to the South Pole as the "first-ever commercial expedition" to "the most remote destination in the world." Unfortunately, this year's departure, limited to 14 people, already is sold out. But repeat excursions are planned for 1988 and 1989.

The trip begins in Miami with a flight to the Chilean capital of Santiago. After an overnight there, participants will fly south to the Chilean port city of Punta Arenas for two nights. From Punta Arenas, they fly over Drake Passage and the glaciers and ice fields of the Antarctic Peninsula to Mount Vinson Base Camp in the Ellsworth Range, Antarctica's highest mountain chain.

Pilot and guide will monitor the weather, and when it is favorable passengers will board a long-range Twin Otter aircraft for a flight across the polar ice cap to the Thiel Mountains for an overnight and then onward the next day to the South Pole.

At the South Pole, the tour group will "toast their accomplishment with champagne," says Society Expeditions, take photos and do some exploring before returning to the Thiel Mountains again for the night. There are return stops also at Mount Vinson Base Camp and Punta Arenas. In Antarctica, the group will stay in Polar Haven huts, which are large insulated tents designed for polar temperatures.

The cost this year is $34,950 per person (double occupancy) for land arrangements. The approximate round-trip air fare between Miami and Punta Arenas is another $1,170.

For information: Society Expeditions, 3131 Elliott Ave., Suite 700, Seattle, Wash. 98121, (800) 426-7794 or (206) 285-9400.

Burma and Thailand: Burma is another nation not easily visited, although a limited number of tourists are welcomed for no more than a week's stay. The Smithsonian Associates Travel Program has scheduled a three-week Asian trip in January that features seven days in Burma and 10 days in neighboring Thailand.

First stop on the itinerary is the Thai capital of Bangkok for a look at the opulent Grand Palace. Then the group travels north to Chiang Mai, a major Thai handicraft center, where a day excursion to visit the villages of the hill tribes is planned.

In Burma, the tour visits the colonial city of Rangoon; the plain of Pagan, filled with temples and archeological remains that date back to the 12th century; the city of Mandalay; and Kalaw, once a favorite hill station retreat of the British.

A Smithsonian study leader will accompany the tours.

Departure is Jan. 9 from Seattle. The round-trip cost from Seattle is $4,275 per person (double occupancy). Air fare between Washington and Seattle is additional. Smithsonian membership is required; the fee is $35 single or $45 double.

For information: Smithsonian Associates Travel Program, 1100 Jefferson Dr. SW, Washington, D.C. 20560, 357-4700.

Mali: This French-speaking West African nation is perhaps best known for one of its ancient trade capitals, the exotic city of Timbuktu (Tombouctou) on the Niger River. Cross Cultural Adventures, an Arlington tour company, has scheduled a January trip to Mali that concludes with a river excursion to Tombouctou.

Departure is from New York via Air France to Paris and Bamako, the Mali capital. After a night to relax, the group -- limited to 10 -- travels by minibus to Dje'nne', reputed to be the oldest city in Africa and famous for its huge adobe mosque. The trip takes about seven hours. The bus arrives in time for a look at Dje'nne''s weekly market.

From Dje'nne', the minibus rolls through hill country to Sanga and the Bandiagara Cliffs. From here, the group sets out on a three-day walking tour past Dogon villages, camping along the way. The walks are described as "easy," and porters carry baggage and prepare meals.

From Mopti, a market town on the Niger, the group boards a large pirogue for the three-day river journey to Tombouctou. Nights will be spent camping on the bank. In Tombouctou, an afternoon camel ride to nomad encampments in the desert country outside of town is planned. The group then returns by air to Bamako for two nights.

When not camping, participants will stay in bungalow accommodations (with shower) in small towns and in modern, full-service hotels in Bamako, Mopti and Tombouctou.

Departure is Jan. 16. The cost for land arrangements is $2,650 per person (double occupancy). Approximate air fare from Washington is an additional $1,612.

For information: Cross Cultural Adventures, P.O. Box 3285, Arlington, Va. 22203, 532-1547.

Borneo: The third largest island in the world and divided between Indonesia and Malaysia, Borneo invites the traveler who is looking for a cultural adventure. Rei Adventures has scheduled a 16-day trip in December that includes visits to tribal villages as well as a three-day hike to the top of 13,455-foot Mount Kinabulu -- all in Malaysian Borneo.

Departing from Los Angeles via Malaysian Air, the group connects in Kuala Lumpur for the flight to Borneo. A highlight of the Borneo visit is a boat trip up the Skrang River, where the group will meet and take meals with members of the Iban tribe. Accommodations will be in longhouses, the tribal stilt houses beside the river.

Also on the itinerary is a visit to the Sepilok Reserve, a forest region set aside for the protection of wild orangutans.

The tour concludes with an optional three-day hike up Mount Kinabulu, Borneo's highest peak. The strenuous route begins in tropical jungles and ascends to cool, rocky moorlands. Accommodations are in mountain huts described by Rei as "very comfortable."

The final day is spent at a beach hotel on the tropical coast.

The trip departs Dec. 3. The cost from Los Angeles, including air fare, is $2,640 per person.

For information: Rei Adventures, P.O. Box 8090, Berkeley, Calif. 94707-8090, (800) 622-2236.

Maldive Islands: More than 2,000 islands make up the mostly Moslem Republic of Maldives in the Indian Ocean southwest of India and Sri Lanka. In recent years, the former British territory has begun welcoming tourists to its many fine sandy beaches. World Expeditions offers one- or two-week cruises of the islands -- many uninhabited -- in dhonies, the traditional Arab sailing vessel.

The Maldivian crew charts a course to take advantage of the beaches for swimming and the coral reefs for snorkeling. There are stops at fishing villages and -- for a taste of civilization -- an occasional resort island. Passengers sleep aboard or in tents on the beach. A shipboard cook prepares the meals.

Departures are every Monday from Male. Singapore Airlines flies from the West Coast via Singapore to Male, the Maldive capital. World Expeditions often links a week of rigorous trekking in Nepal with a relaxing cruise in the islands. Flights are available from the Nepalese capital of Katmandu to Male.

The cost for an eight-day cruise is $565; for 15 days, $960. The approximate round-trip air fare from Los Angeles or San Francisco to the Maldives is $1,400.

For information: World Expeditions, 291 Geary St., Suite 619, San Francisco, Calif. 94102, (800) 541-3600 or (415) 362-1046