For every American dollar you plunk down on a counter in Canada this summer, you'll pick up approximately $1.25 in Canadian currency. You'll be saving 25 percent on every dollar you spend once you cross the border into this exuberant, multi-cultural country.

As Canadians, our family has mixed feelings about the Canadian dollar riding at an all-time low. But greed prevails, and we will spend this August wallowing in the delights of Toronto, Ont.

Toronto is an easy shot for Washington-area residents: 570 miles by car, two hours by air. You can spend a huge sum in some of the world's most luxurious hotels, restaurants and shops, but you don't have to.

Our strategy is to rent a house for August in the Beaches area of the city. We have rented from an archeologist off on a dig in Egypt and from a young, English school-teacher couple returning to England for a visit. This year we are renting from a Toronto family spending August at their summer cottage.

We pay $700-$800 Canadian (about $525-$600 American) for a completely furnished and outfitted home. Ours have ranged from three to five bedrooms. Each has had a garden, deck or patio and the big front porch or "verandah" often found in Toronto homes.

The Beaches area of Toronto is our favorite. Our houses have been half a block from a sandy beach and tree-lined boardwalk running three miles along Lake Ontario. They have also been half a block in the other direction from a delightful section of old Queen Street which runs parallel to the lake and is packed with unusual small stores and cafes.

Every few minutes, a bright red trolley or street car careens noisily along Queen Street toward downtown Toronto. It links up with the city's clean and efficient public transport network of buses, subways, ferry boats and the Government of Ontario (GO) train for commuters. Apart from the GO train fares and the ferries, 65 cents will take you anywhere in Toronto (kids under 13, 25 cents).

To locate a house in Toronto, advertise your requirements and price range in one of the city's three daily newspapers. Our choice for this purpose is the Toronto Star. Knowing our own preference for neighborhoods, we advertised this year only in a small community paper in the Beaches and received 28 responses. A lot of families leave Toronto for the month of August. Several houses were less expensive (farther from the lake) than the one we chose.

We also drew a variety of interesting propositions: less rent, for instance, if we'd mind the family dogs or keep an eye on a teen-ager. One house comes equipped with a canoe and kayak.

For a shorter stay, or if you don't want to be bothered choosing a house, there are The Promenade modern apartment buildings located in Deer Park, a lovely neighborhood of parks and mansions. The fully-equipped luxury apartments are rented by the week or month in sizes ranging from bachelor (Canadian for efficiency) to two-bedrooms.

Typical rates for a one-bedroom with sleep sofa in the living room, in American dollars: $488 per month, $288 for two weeks, $158 for one week.

Another delightful and economical way to stay in or near Toronto: through Metropolitan Bed and Breakfast, which maintains a list of 75 residents who offer overnight accommodations in their own homes, plus a full breakfast for rates averaging $25 single to $35 double ($19 to $26 American).

Elinor Bolton describes her "B and B" hosts as "not at all the conventional tourist-home operators. These are people who are proud of their homes and want to show them off and share them. And the breakfasts are not 'Continental' but generous Canadian-style meals prepared by hosts who like to cook and visit with their guests."

The accommodations themselves are often unusual: a mansion in the center of town with a startlingly modern decor inside a red-brick Victorian shell; an authentic, newly renovated French Norman castle; a country estate, complete with pond, swimming pool and running deer. And if you'd like a little adventure, one older home reputedly has a ghost on the prowl.

Thirty years ago, Toronto was the staid old dowager of North American cities, predominantly British and so stuffy that it was snickered at as "Toronto the Good" by debonair Montrealers. Restaurants and movie theaters were closed on Sundays and the nearest cocktail bar was in Buffalo, N.Y.

Not so any more. Toronto is now colorful, vigorous, lively.

More than half of its nearly 3 million residents were born outside of Canada. The "new Canadians" from some 80 different countries have turned the city into a mosaic of ethnic neighborhoods.

Canada is officially a bilingual country: English and French. Americans crossing the border for the first time notice immediately that all official signs, packages and labels appear in the country's two languages.

There are hundreds of neighborhood restaurants where native foods are served at reasonable prices in casual surroundings. The Toronto telephone directory lists restaurants by ethnic cuisine. Occasionally, there's a curious combination: Our favorite is "Ginsberg and Wong" in downtown Toronto.

Because Toronto has one of the lowest crime rates in North America, it is a pleasure to explore, with many of its attractions downtown and on the waterfront. In August and early September, the days are warm, averaging in the high 70s, and the nights are cool.

Much of our low-cost fun is centered on the shoreline of Lake Ontario. Old-time ferry boats ($1 for adults, half-price for seniors, 25 cents for kids) leave the dock in downtown Toronto every 20 minutes for the Toronto Islands, where there is bathing on sandy beaches, boat rides on the shady lagoons, a reproduction turn-of-the-century town called Centreville and scores of other activities.

"Please Walk on the Grass" signs appear throughout the islands (and in all of Toronto's 200 parks).

More spectacular is the 96-acre Ontario Place--built on three, man-made islands linked with walkways--also on the waterfront in central Toronto. One island has village-like groupings of small shops, snack bars, restaurants and pubs. Another is an entertainment area with an outdoor amphitheater and giant 6-story Cinesphere movie theater. The third island, Children's Village, is totally for kids with several play areas obviously designed by someone with the heart of a child, or a very good memory. In the large water-play area, kids shoot water guns, float around in giant inner-tube rafts, splash in and out of pools and cascades of water and generally run amok while their elders watch from grassy slopes. When it's time to leave, the sopping youngsters pass through a tiger-shaped hut where warm circulating air dries them off for the trip home.

All Ontario Place (except food and drinks) is included in the admission price: $3.50 for adults, $2 for teens, 50 cents for kids. Visitors over 64 are admitted free, as they are to many of Toronto's play areas and events.

August also takes us to Toronto for the Canadian National Exhibition, or the "Ex," the oldest and largest permanent exhibition in the world. This year it runs Aug. 18 to Sept. 6. Like a giant street fair, the "Ex" sprawls over many acres on the waterfront.

One entire building at the "Ex" is devoted to Canada's food products; samples and low-cost snacks are everywhere. A giant midway of rides and games, a huge grandstand with big-name entertainment and a fireworks display at closing time nightly are among the "Ex's" many lures.

Admission price: $3 for adults, $2 for teens, 50 cents for kids and those over 64, free.

And then there's the Ontario Science Center, Harbourfront, the new Metro Toronto Zoo and much more.

The best buy in vacations just could lie straight north--yours until the currency rate changes.