Maya ruins within the jungles of the southern states of Quintana Roo, Campeche and Chiapas in Mexico will be the focus of an expedition leaving April 5 and returning April 20. Difficult to get to, the sites are reached by hiking, dirt tracks and rivers.

Sites include those of Rio Bec, Xibalba, Chiapas, Yaxchilan and Bonampak. Participants also will visit the Lacandon Maya in the remote Chiapas rain forests, exploring ruins, villages and the home of Chan K'in Viejo, the 101-year-old Lacandon elder of Naja. Some nights are expected to be in camps within the plazas of the Lacandon Maya villages, and each traveler is requested to take along a sleeping bag and tent.Cost is $2,850 per person, double occupancy, including meals and air fare from San Antonio, Texas. For more information, contact Far Horizons Cultural Discovery Trips, P.O. Box 1529, 16 Fern Lane, San Anselmo, Calif. 94960.

-0 EXPLORING CANADA: Western Canada will be the focus of a July 6-18 trip being sponsored by the North Orange County (Calif.) Community College District. An itinerary includes the Calgary Stampede, Banff and Lake Louise in the Canadian Rockies, a snowmobile ride on the Columbia Icefields and a visit to Victoria's Butchart Gardens and Vancouver.

Cost is $2,899 per person, double occupancy, including round-trip air transportation. Motor coach, airport transfers, accommodations, American breakfasts, seven dinners, sightseeing admissions, guided city tours, round-trip ferry transportation between Vancouver and Victoria, baggage handling and tips and taxes are part of the price. For more information, call the college district at 1000 N. Lemon St., Fullerton, Calif.92632-1318.