There are countries, and then there are mountains: The two entities overlap, but sometimes they seem almost mutually exclusive. Take Mexico's three great volcanoes, Pico de Orizaba (also known as Citlaltepetl), Popocatepetl and Ixtaccihuatl. When you are on them you are still in Mexico, but you are also Someplace Else, a high, weird, scorched and frozen Ur-world stranded in the sky.

Today the peaks of Mexico have been discovered by legions of well-outfitted adventurers and their guides, but when I first went there 16 years ago it was a different story. I first visited the Mexican volcanoes -- specifically 17,887-foot Popocatepetl -- back in 1974. I was living in southwestern Colorado, and a friend and I decided to go down to Mexico and try to scale Popo, as the peak is known colloquially.

It was a spur-of-the-moment decision, reached at 2 a.m. on Saturday night in a local bar, and as I recall, our reasons for going had a lot to do with the fact that both of us were unemployed and had also been recently discarded by our respective girlfriends. We were desperate characters, I guess: We had almost no money, and less sense. We hitchhiked across the mountains to the town of Ridgway the next morning, and caught the bus south to Albuquerque and on to El Paso.

We looked so ragged and strange, in our worn climbing garb, lugging ice axes, ropes and rucksacks, that the Mexican border officials wanted to deport us on sight. At last, thanks to the intercession of our Hispanic taxi driver, they relented, and we made it to the Juarez railway station just in time to board the train south to Mexico City.

Looking back on the trip now, through the glow of past time and nostalgia, it seems like an enchanted, crazy, wondrous journey, and it probably really was: Hope and Crosby, Kerouac and Cassady, Hillary and Tenzing -- On the Road to the Magic Mountain. We were so broke that we were reduced to buying terrible tinned meat and rubbery cheese in Mexico City to eat on the mountain. We rode another train, a diminutive and rickety local, from the capital to the town of Amecameca, at the base of Popo.

The volcano floated above us in the dry blue air now, disembodied, monstrous, making our hearts leap into our throats. We knew the standard route to the summit was little more than a footslog, a steep stroll over loose rock and snow, nothing technical -- but still, the mountain was so huge. We were ecstatic.

More hitchhiking took us up through tiny villages, stony fields, fog-shrouded clumps of timber, up to Tlamacas, the hostel at the 13,000-foot level on the ridge between Popo and Ixty. Mexico City was only 45 miles away, but we were already in another realm, a separate reality.

As evening fell, clouds coalesced, swallowing the world below. The view to the south, up Popo's near flanks, was awesome: gnarled Plutonian crags, fields of snow and ice, steep wastes of black gravel... . It looked like the dawn of time, or maybe the end of the world. An occasional whiff of sulfur drifted down to us from the distant summit, reminding us that the mountain was still very much alive. Popocatepetl is an Aztec word meaning "Smoking Mountain," and there was a major eruption as late as 1802.

There were strange people at Tlamacas, too, escapees from a Graham Greene novel, or a Mesoamerican knockoff of "Twin Peaks." The lodge at Tlamacas was full of youthful norteamericano evangelical Christians on a religious retreat; they descended on my comrade and me with conversion in mind, and after cadging a free dinner off them we fled to the parking lot, where a silver-haired Brazilian gangster was holed up in an Airstream trailer with his voluptuous 19-year-old mistress.

He was driving home from Miami to Rio, he said, towing the Airstream behind his brand-new Cadillac. He showed us his Uzi, his pearl-handled .45 automatic and his stiletto, and then he produced a bottle of Herradura "Blue Horseshoe" tequila. We drank, to crime, high mountains and romance, till the tequila was gone and the 19-year-old was unconscious, head on the table, her lovely face resting on masses of thick gleaming black hair. My climbing partner and I staggered back to our bunks in the hostel across the fog-shrouded parking lot. Popo was hidden in the murk above, mysterious, implacable.

The next morning, the weather was still bad: Clouds cloaked the mountainside, reducing visibility to a couple of hundred feet. We decided to move on up to the mountaineers' hut at Las Cruces, halfway up the standard route up the peak, and try for the summit the next day, when the weather might improve. We shouldered our enormous packs and began plodding up the trail along the volcano's northern flanks.

We rounded a corner and came upon three young Indians, muffled in knit skullcaps, blankets and heavy woolens against the chill, standing next to the track. They had drawn a minatory line across the trail in the loose gravel and dust, and decorated it with what looked like voodoo and hex signs. As we passed, they smiled at us -- cryptic, disturbing smiles.

"Buenas tardes, Senor," one of them said, with heavy emphasis on the "tardes" and a tone of exaggerated, ironic politeness. My friend had just read the Carlos Castaneda books, and as we went on up the trail he whispered to me, "They're brujos -- sorcerers. That's what they are. Guarding the mountain." Who knows? It was an eerie place.

The hut at Las Cruces was a disappointment. We had had visions of a pristine rock-and-log mini-chalet, but what we found was a battered metal cubicle, spray-painted with graffiti and surrounded by acres of garbage-strewn screes. Empty cans and wrappers were everywhere, and toilet paper banners fluttered from the boulders. It was so bad it was hilarious: I imagined armies of climbers, toting ice axes and aerosol paint cans, tossing armloads of garbage across the mountain.

Gigantic ravens soared through the fog, croaking and cawing, adding to the strangeness of the scene. Rusty iron crosses commemorated the scores who had died on the mountain over the decades, most of them lost in storms. We spread out our sleeping bags on the concrete floor of the hut, ate the last of our meager rations and tried to get some sleep.

It was an uneasy night: Something, either a giant raven or a giant rat, scuffled and thumped in the attic of the hut, and the mountain rumbled and grumbled. Once, I got up and went outside; there was an incandescent glow burning through the mists above, from where I knew the summit was. Again, I was thrilled and enthralled: I was seeing the fire from the Earth's core, reflected up from the depths of Popocatepetl's crater. It seemed marvelous.

The next morning the weather was still bad, visibility still almost nil. We climbed to within a couple of hundred feet from the rim, plodding through ankle-deep volcanic rubble, tiptoeing up ramps of frozen snow. Then the clouds closed in even thicker. We were hungry, tired and far, far from home. We took a long last look up at the dim shape of the summit, and started back down. It took us five days to get home.

Since then, I have been back to the volcanoes twice, once to Citlaltepetl (the highest, at 18,700 feet) and once, again, to Popocatepetl. Both these later trips were much better organized than that first crazy expedition to Popo.

On the trip to Citlaltepetl, two California climbers and I again rode the train to Mexico City, this time from Mexicali. From Mexico City, we rode the bus southeast to Puebla and on to Tlachichuca, where we hired a driver to take us on up to the mountaineers' hut at Piedra Grande, at the 14,400-foot level on the peak's lower flanks.

We never made it to the summit: A storm had dumped deep, avalanching snow on the volcano, making climbing hazardous; a few days before, two young German climbers had vanished into a snow-covered crevasse high on the summit cone, never to be seen again.

But, again, we had a fine time. The hut at Piedra Grande was lovely, a veritable chalet completely unlike the one on Popo. There were a couple of Mexican climbers at the hut, young businessmen from Tampico, friendly, elegant chaps. They had come well-stocked with food and alcohol, and were waiting for conditions on the peak to improve. We drank with them, and talked, the kind of golden conversations that seem to occur when strangers meet in high, wild places. Far into the night, while the wind boomed outside, we talked of mountains, of deaths, of loves, of the sad and bitter history between our two countries.

The summit is what makes everything happen in mountaineering, but it isn't everything.

My second time to Popocatepetl, I finally managed to get to the top, and stared into the monstrous, smoking crater. I spent nearly a week bivouacked just below the summit, on a ledge hacked and scraped out of the loose lava rock. There was just room for my tent; my water supply came from a small snowfield just above my campsite.

This was really the sweetest trip: watching the storms roll across the world below, phosphorescent sunsets on the snows of Ixtaccihuatl across the void, mists drifting over the screes and the mightiest skies I have ever seen, before or since. The isolation and loneliness only added to the beauty. When I finally went down the mountain, I felt as if I were leaving paradise.

Rob Schultheis reports from Afghanistan and works on various film projects in his spare time. WAYS & MEANS

GETTING THERE: United flies from Washington Dulles to Mexico City for $355 round trip, with restrictions; Mexicana flies from Baltimore-Washington International for $380 round trip, with restrictions. From Mexico City, which is about 45 miles from Popocatepetl, you can reach Amecameca, the closest town to the volcano, by bus or rental car. It's another hour's drive by car or taxi to Tlamacas, the base camp for mountain climbers, where there is an inexpensive lodge (about $3 per night) with bunks, bathing facilities and food.

WHEN TO GO: October through March, the drier season, is the best time to climb the volcanoes; skies are generally clear, storms rare. The mountains are crowded at that time of year, though, with mountaineers from all over the globe coming to grab some altitude. Days are pleasantly cool, but because it can get frigid at night, it's a good idea to bring several layers of clothing. And you should bring all your own hiking gear; it's not easy to buy or rent locally.

GUIDES: Among the guide services in the United States that lead group trips to the volcanoes:

American Alpine Institute, 1212 24th St., Bellingham, Wash. 98225, (206) 671-1505. A 14-day, two-part trip from Mexico City to Popocatepetl, Ixtaccihuatl and Pico de Orizaba, departing Nov. 4, Nov. 25 or Dec. 16, is $1,180. The trip can be broken into one of the two parts, an eight-day hike up Popo and Ixty for $710 or a six-day climb up Orizaba for $580. Mountain Travel, 6420 Fairmount Ave., El Cerrito, Calif. 94530, 1-800-227-2384. A 12-day hike up Popo and Orizaba, during which mountaineering techniques are taught if necessary, is $925 to $1,075, depending on the number of participants. Departures from Mexico City are Oct. 20 and Dec. 15.

REI Adventures, P.O. Box 88126, Seattle, Wash. 98138, 1-800-622-2236. An eight-day "strenuous" climb up Popo and Ixty, departing from Mexico City Feb. 10, Nov. 9 or Dec. 7, 1991, is $975.

You can also look for excursions in the classified ads of mountaineering magazines such as Climbing or Rock & Ice.

INFORMATION: Mexican Ministry of Tourism, 1911 Pennsylvania Ave. NW, Washington, D.C. 20006, 728-1750.