As the train hurtles south from Zurich, rain slashes at its windows. The Alps ahead are obscured by mist; the wind bends the trees. On board, despite the late spring date, passengers sit swathed in sweaters.

The train climbs, climbs some more, then plunges into the darkness of the 10-mile-long St. Gotthard Tunnel. When it emerges some minutes later, the sensation is reminiscent of "The Wizard of Oz" when lo! the film changes from black-and-white to color.

Indeed, here on the other side of the Alps, the sky is blue, the air is warm and fragrant, and the girls sunning themselves in the backyards along the right of way are wearing bikinis.

We are in the Ticino, the Italian-speaking canton of Switzerland, often bypassed by the average American tourist but known to European cognoscenti as the "Swiss Riviera."

In this Mediterranean-flavored region, thrust like a spearhead into the lake district of northern Italy, palm trees -- not to mention figs, olives, eucalyptus and mimosa -- cohabit with Alpine chestnuts and firs; porticoed Italianate villas replace chalets; and the restraint of the Germanic north dissolves in Latin joie de vivre. Workers in shops and banks here take siestas; menus are more apt to boast pasta than rosti (the traditional Swiss potato dish), and when residents say they are going to "the city" to shop, they mean Milan, not Zurich or Geneva. Yet this is most definitely not Italy.

The Ticino is achingly lovely. George Steiner, the eminent critic-scholar, might well have had the Ticino in mind when he recently wrote, "The physical beauty of Switzerland is often such as to rebuke rejoicing. This power of loveliness to sadden, to imply terror, is difficult to paraphrase." With its green lakes shimmering beneath snow-streaked mountains; its lush landscapes framing quaint hillside villages; and its untamed valleys bespeaking the wilderness primeval, it offers scarcely a view -- whether from cable car summit or waterfront promenade -- that does not bring a lump to the throat.

Ironically, however, the Ticino was, until recently, what some natives call "an overlooked canton." Though the Swiss, after numerous struggles, finally wrested the Ticino from the Italians in 1803, they tended to ignore their only territory south of the Alps. Thus, cut off from the mainstream of Swiss activity and cursed with increasingly infertile land, the poverty-stricken Ticinese were forced to emigrate.

It was not until this century -- indeed, not really until after World War II -- that (thanks to tourism) the Ticino began to know substantial popularity and prosperity. And still today some Ticinese feel politically ignored. They chafe at the absence of an airport of consequence in their canton; they complain about the lack of a university for studying Italian. And it was not until five years ago that a major automobile link with the rest of Switzerland was built.

What is more, the Ticinese worry about losing their identity, as newcomers -- escaping the dourness of the north and the hurly-burly of the south -- swarm in. To this have-your-cake-and-eat-it land come the German lady who loves the Ticino's "synthesis of north and south"; the Italian commercial pilot who revels in the dependability of the Swiss federal railways and Swissair; the American girl who works at a newsstand because the area is "so safe" and "so romantic." By settling in the Ticino, they join a succession of the area's admirers that has included Isadora Duncan, Paul Klee, Carl Gustaf Jung, Erich Fromm, Hermann Hesse (buried near Lugano) and Erich Maria Remarque', whose widow, the actress Paulette Goddard, remains in the area.

Such "immigrants," along with the majority of Ticinese, live in the southern part of the canton. Although most of the Ticino -- which has a population of about 263,000 and is about the size of Rhode Island -- lies, relatively undeveloped, in the north, its prime population and tourist centers are situated on those shores of Lake Lugano and Lake Maggiore that are not in Italy. This domain, less crowded than its Italian counterpart, is divided into the Sopra (upper) and Sotto (lower) Ceneri -- named for Mount Ceneri, which rises between the two lakes. And here, determinedly asserting their individuality, flourish the destinations of Lugano, Ascona and Locarno.

A lively, cosmopolitan city, Lugano, with its population of 35,000, is the largest Ticinese center and the most conveniently reached. It is part of one of Europe's primary north-south arteries, with elevated roadways, tunnels and rail lines that funnel traffic between Germany and Italy.

Fronting on Lake Lugano as it follows the crescent-shaped shoreline, it also climbs up the slopes behind it and spills into a nearby valley. Two sentinel peaks -- the 3,053-foot Mount Bre and the 2,995-foot Mount San Salvatore -- watch over it, their summits offering dazzling see-forever views of the surrounding region, including, on ultra-clear days, the Po Valley and hints of the Appenines. In another favorite local scene, San Salvatore is viewed across the water with a palm tree splayed in the foreground -- looking, for all the world, uncannily like a slice of the South Seas.

This image tarnishes somewhat when you realize that Lugano is a major banking center and boasts nearly 50 banks -- strongly supported by Italians seeking the anonymity of Swiss bank accounts. But, unless you happen to be in Lugano on business, chances are the city's commercial aspect will be overshadowed by its relaxed and relaxing demeanor.

Indeed, though the Piazza della Riforma, the main town square, may be surrounded by financial institutions, it is also filled with children's volleyball games on Saturday afternoons; chess games conducted on large, painted-on-the-pavement chessboards; and diners sipping aperitifs and munching pizza under the red, white and blue umbrellas of the square's several trattorias.

Leading out from one side of the piazza is the Via Nassa, Lugano's chief shopping street. Narrow and porticoed, it, like much of old Lugano, reflects the days when the city was an Italian bailiwick. Just off the piazza's other side spouts a fountain that appears to have been created from hunks of lava, and immediately beyond this is the two-mile-long lakefront promenade. Hour after hour is easily spent here, wandering among the flower beds and open-air sculptures; reading on a bench among the trees; watching the boats bob on the lake.

Lugano does, it is true, boast specific sights -- chief among which are the Church of Santa Maria degli Angioli with its 16th-century Luini frescoes, "Crucifixion" and "The Lord's Supper"; and the Villa Favorita, which houses works by Rembrandt, Du rer, Bruegel, Rubens, El Greco, Holbein and Van Dyck, in what is reported to be Europe's leading private art collection.

But, ultimately, the lake draws you back. When I was there, it was about to storm, and the concierge at the Hotel Splendide Royal, facing the lake, accurately suggested that I watch nature's light show. When it was over, I took a regularly scheduled boat to Morcote, where I climbed to an elaborate cemetery cut into the side of the hill. On another occasion I sailed to Gandria, a fishing village built almost vertically over the water with inclines so steep that residents claim to fit their chickens with bags to keep the eggs from rolling away.

On Lake Lugano, the Italian border cuts off only a small piece of one spur; on Lake Maggiore, the tale is quite otherwise. Four-fifths of this larger body of water lies in Italy and all but the briefest sails necessitate producing a passport. The area around the Swiss section, at Maggiore's head, also has a different feel from that of Lugano, because the mountains are more rugged and the villages farther apart. Here, Locarno and Ascona share a flat tongue of land that protrudes into the lake and is divided by a river. According to many, the two resorts maintain a friendly rivalry; one local official, however, says the river is psychologically "a Berlin Wall."

The smaller Ascona fancies itself the more chic, with its devotees citing the presence of artists and art galleries as one piece of proof. The heart of this old, labyrinthian fishing village has been restored into an aggregate of smart boutiques, garden restaurants and food shops, opening off cobbled, arcaded walkways and tiny, hidden courtyards. Every window display here reveals immaculate taste; enter a confiserie for a bit of chocolate and you'll find pieces individually packaged in gift boxes just 1-inch square.

Along the lakefront, groomed plane trees stand at precise intervals, benches are regularly spaced, and the flower beds are color coordinated. Even the dogs seem to walk with dignity. Almost needless to say, prices are commensurate with appearance, and one of the hills behind Ascona is so covered with the elaborate homes of wealthy Germans that some residents have dubbed it "Monte Mercedes."

Just a 10-minute ride away, Locarno is more down-to-earth. While exuding its own brand of sophistication and charm, it also reveals a happy spontaneity -- in the casual plan of its subtropical gardens, the informality of its cafe's and the friendly atmosphere of its shops that do not make customers feel like the proverbial china-store bulls.

It has its share of antiquity in its archeological collection, which contains specimens from Roman times and is housed in the 14th-century Visconti Castle, erected by the ancestors of the Italian film director, Luchino Visconti. (Currently sharing these premises is a 40-piece collection of works by the Dadaist Jean Arp, who lived in Locarno for several years.)

Among Locarno's other attractions are the Sanctuary of the Madonna del Sasso, high above the city and boasting paintings by Bramantino and Ciseri; the building where the Pact of Locarno, a series of agreements by European countries seeking to insure peace, was signed in 1925; and the 17th-century Chiesa Nuova, or "New Church," elaborately decorated with frescoes and stucco work.

Much of Locarno's best, however, is revealed in unplanned moments. There is the sensation of discovery when, while strolling the cobbled hills of the Old Town, you chance upon a 16th-century courtyard surrounded by loggias and highlighted by a stone well complete with wooden bucket. Wonderment mounts as, in a half-hour's ascent by funicular and cable car, you rise from the perfumed sensuality of the nearly tropical lakeside to the bracing freshness of Alpine heights. And pleasure stirs in a cafe' off the arcaded Piazza Grande, or on a balcony of the Hotel La Palma au Lac.

Locarno, along with the rest of the Ticino, is ideally situated for excursions both long and short. Within reach by day trips are Venice, Florence, St. Moritz, Lake Como, Stresa and the Rhone Glacier. Within a fraction of an hour is Bellinzona, the Ticino's capital, with its medieval castles and botanical gardens on the larger Brissago Island. Purportedly the scene of pagan orgies in the distant and not-so-distant past, the island today, with its beautifully laid out stands of bamboo and cypress, papyrus and banana, demonstrates the wide variety of flora that can be grown in this unlikely location.

Finally, to fully appreciate the Ticino, one must know a little of its valleys, some of the best of which radiate from Lake Maggiore. Perhaps the most exciting of these is Val Verzasca, a dark, narrow stretch rent by an electric-green, boulder-strewn river. Dwellings in the villages here -- inhabited now primarily by vacationers -- are built of gray, granite slabs placed on top of each other without mortar; often located on the sides of hills so steep they might well be called cliffs, they appear simply to hang in space.

Throughout the valley, little chapels dot the roadside, many bearing frescoes attesting to the Ticinese talent in this field. And, at a spot called Lavertezzo, a picturesque, double-arched bridge spans the river and leads to a typically Ticinese eating place known as a grotto.

Originally, grottos were precisely that -- caves where homemade salamis, cheeses and wines were kept cool. Today, most have evolved to more sophisticated outdoor restaurants. But in the grotto at Lavertezzo, the proprietor still serves homemade sausage with the local merlot wine.

Like most valley people, he is rather close-mouthed, and when he speaks it is in the valley's dialect. Yet, through an interpreter, he will tell an American about all the relatives -- descendants of impoverished immigrants -- he has in California and how, sometimes, he thinks of visiting them. But then he decides there are too many. And besides, he lets it be known that life is fine where he is -- on the banks of the rushing waters of a valley in the Ticino.