Travelingthe world through stamps has always been the most economical way to go, and the opportunities are almost limitless.

Many philatelic travelers are taking in Canada this year. Canada has much to offer because it has Expo 86, a world exposition at Vancouver, and is also celebrating the 100th anniversary of both the founding of that city and the first transcontinental train travel.

The striking Canada Pavilion and the Expo Center, a gleaming 17-story geodesic dome, appear on two 34-cent Canadian stamps scheduled for domestic first-class mail. A 39-cent stamp for first-class mail to the United States pictures the evolution of communications from the telephone to space satellites, and a 68-cent stamp depicts ancient and modern rail cars. In addition, there is a $5 stamp in the Canadian Parks series that pictures La Maricie National Park in Quebec.

Also popular with stamp collectors are the countries of southern Europe.

France, which annually puts out more stamps for tourism than any other country, has been devoting most of its latest issues to historic structures. One stamp pictures the 16th-century Norman manor of St. Germain de Livet. Others picture the walled castle of Leche on the Loire River and the religious sculptures of the church of Notre Dame in Vaux.

Italy continues its series of quartets of commemoratives devoted to tourism with stamps showing a view of the villas of Acitrezza overlooking a vista of ocean and islands; the square and church of the isle of Capri; the vast domed church at Merano; and the expanse of sea at San Benedetto del Tronto with a gleaming white lighthouse in the background.

Issues from Spain display the interior courtyard of the Monastery of Lupiana at Guadelajara, the Cathedral of Ciudad Rodrigo at Salamanca, Nerja's Balcony of Europe, an ancient watchtower, and the Calella lighthouse in Barcelona. A stamp from Spanish Andorra offers a view of the town of Pel.

Sweden, Norway, Denmark, Finland and Iceland are offering a philatelic tour of Scandinavia this year. Each country has put out a pair of what are called Nordic stamps devoted to a common theme. Each country's stamps are devoted to "twin towns," a long and strong tradition in Scandinavia. More than 200 Finnish communities, for example, have sister towns in the other four countries. The Nordics are issued every three years.

Belgium has issued stamps picturing two of its cities, while Luxembourg displays its medieval fortresses on a set of three. Another trio from Ireland is devoted to its picturesque inland waterways, showing a canalside village, a turreted castle on the banks of the Shannon and anglers in one of the many streams.

For the more adventurous armchair tourists, there are the sights of Afghanistan on a set of seven and three stamps from Nepal. The Afghan stamps depict the ruins of the Guldara Stupa, the tomb of Mirwais, a statue of Bamyan, the ruins of the No Gumbad mosque, the Puke Kheshti mosque, the arch at the entrance of the Bost citadel and the minaret of Ghazni. The three from Nepal show the Temple of Jaleshwar, the Temple of Sahileshwari and Phoksundo Lake