Retirees Take to the Trail on Adventure Excursions : Tours: As seniors stay more active, tour operators are taking their clients off the bus and onto the river raft, the safari Jeep and the scenic mountaintop.

Once upon a time, there was the adventure travel business and there was the senior travel business, and seldom did the two meet. But now, as Americans retire at earlier ages and stay healthy longer, “soft adventure” for seniors is in high demand.

The result is that longtime operators of tours for seniors are lowering their minimum-age requirements, putting on safari hats and going into the adventure business. At the same time, longtime operators of adventure tours are easing up on the physical demands of some itineraries and going into the seniors business. For energetic travelers who are 50 or older and like traveling in a group, this means a wider world of choices.

The most obvious example of this trend is Overseas Adventure Travel of Cambridge, Mass., a 17-year-old firm that last month offered its first series of tours aimed at travelers age 60 and over. But other well-known organizations, including Elderhostel and Saga Holidays, are either planning or running trips for seniors that feature hiking, biking and other trappings of outdoor life.

For Overseas Adventure Travel (800-221-0814) spokeswoman Marybeth Bond says, the move was a natural response to the demographic drift of the company’s clientele. On the company’s most popular itineraries, the average traveler’s age had been increasing yearly and recently passed 50.

To tailor a product to older travelers, company officials redesigned several tours, aiming to increase comfort of lodgings, reduce the number of hours spent in transit, emphasize local cultures (through dinners in private homes, etc.) and allow travelers to pace themselves by choosing or not choosing additional side trips. Overseas Adventure Travel held to its maximum of 16 travelers per group and set prices at $1,590 per person (double occupancy, excluding air fare to Miami) for 10 days in Costa Rica to $4,790 per person (double occupancy, excluding air fare to New York) for a 17-day safari on the Serengeti Plain of East Africa.

The new catalogue of eight “adventures designed for travelers over 60” went out June 15, pitching effortless camping in the Sahara, comfortable research ships in the Antarctic and so on. Within a month, says spokeswoman Bond, 10 of the catalogue’s 44 departures for seniors sold out and 172 travelers were booked, including about 100 bound for Morocco and the Sahara Desert.

On Aug. 15, OAT will offer a free pamphlet of 101 tips for mature travelers to those who call (800) 493-6824.

Saga Holidays (800-343-0273), a 43-year-old Massachusetts company, continues to specialize in the mature traveler, but within the last two years has reduced its minimum age for participants from 60 to 50 and added walking and bicycling options to some itineraries. Saga groups usually include 30 to 40 travelers, and sometimes as many as 49. Saga’s trips range from one to four weeks, with prices from about $1,300-$3,000, air fare included.

Claire Gorayeb, Saga’s director of strategic planning, affirms that soft adventure is an area the company plans to explore.

“We think there’s great potential there,” Gorayeb says. Before next year is over, she says, she expects Saga to be advertising soft adventure itineraries, with the first departures within two years.

At Elderhostel (tel. 617-426-7788), program designers have been offering classes on outdoorsy subjects since the organization’s birth in the 1970s, and many of the most avid participants have been well beyond traditional retirement age--”people in their 60s and 70s and even 80s,” says spokeswoman Cady Goldfield. But Goldfield affirms that these days there is substantial growth in adventure-type offerings, and “definitely a convergence” between the offerings of adventure tour operators and senior tour operators.

Last year, Elderhostel officials in Boston curtailed creation of new outdoor adventure programs while they brought in a consultant to set up uniform safety standards. But interest in existing offerings continues to grow, and in February the organization lowered its minimum age for participants from 60 to 55.

The result: Figures from Elderhostel’s program development office show the organization’s count of U.S. “outdoor adventure” courses rose from 59 in 1991-’92 to 188 in 1993-’94, then to 193 this year.

Current catalogues include such offerings as Grand Canyon hiking and camping trips arranged through Yavapai College in Prescott, Ariz.; wilderness canoe trips in Maine, offered through the nonprofit Chewonki Foundation; classes in Utah arranged through Outward Bound representatives.

Elderhostel programs in the United States usually run six nights and carry an average tuition of $335, excluding transportation to and from the program. The group’s foreign programs usually last two to three weeks and carry prices ranging from $900 (for Mexican and Caribbean destinations) to more than $5,000 (for four weeks in Europe or Australia). Elderhostel groups average 30-40 participants.

* Reynolds travels anonymously at the newspaper’s expense, accepting no special discounts or subsidized trips. To reach him, write Travel Insider, Los Angeles Times, Times Mirror Square, Los Angeles 90053.