When I was a boy in upstate Pennsylvania, we used to call the Sears catalogue the "wish book" when it wasn't being used for something else. Today, my wish book is "Worldwide Adventure Travel Guide," published by the American Adventurers Association out in Seattle, Wash. And I keep it in my office.

If you're an outdoors type, or if you're imbued with the spirit of adventure, or if you just like to dream, you've got to enjoy going through the 608 pages of this book, which includes over 3,000 commercial "adventure" trips around the world that are open to anyone who has the money, time and inclination to try one out.

You can climb mountains in Nepal, take a ski tour in Greenland with a dog-sled escort, trek to the top of Kilimanjaro in Tanzania, take a wildlife nature trip through Argentina's Patagonia, fly a glider or take a balloon over the Alps, join a birdwatching tour of Australia, scuba dive on a private island 15 miles off the coast of Belize in Central America, or bicycle, hike, raft, canoe or kayak just about anywhere in the world.

That's only a sample. Some of the trips obviously are not for the flabby or faint-hearted, while others can be enjoyed by your 85-year-old grandmother or your brother-in-law Harry who surfaces from his martini glass once or twice a year just to see if the world is still there.

All of the trips fall into the category of "fadventure travel," a market enjoying a tremendous boom during the past few years, thanks in no small part to the folks out in Seattle, who also bring us a monthly magazine called, of all things, Adventure Travel.

Adventure travel can be physical, cerebral, emotional or a combination of the three. Perhaps the basic premise is that you do something with your time -- a physical challenge or a learning experience -- rather than lie around a hotel, pool or beach. Now that may be utter anathema to some of us (or some of you), but there is a growing cadre of travelers to whom action and adventure hold great appeal.

Take a look at Adventure Travel magazine, which published its first issue in June 1978. In a year, the circulation went from 60,000 to 110,000, and the publishers are projecting 200,000 or more by 1982. Who are the readers? A survey taken a year ago found the median age was 33 1/2 and the average income $35,500. Now, that lets a lot of us out, but you can still dream, can't you?

The magazine has excellent photography and seems something of a hybrid of outdoor, wildlife, conservation and travel writing. But it projects a distinctive image and "feel" that reads back something like this: Adventure travel means challenging the environment and caring about it at the same time.

With these and other notions gleaned in a few months of reading the aforementioned publications, I picked up the phone the other day and dialed Bob Citron, the publisher. Citron had just gotten back to Seattle after a month in Paupau, New Guinea, with his wife, Barbara L. Sleeper, the magazine's editor-at-large.

If their magazine could talk, it would probably sound like these two, excited with life and the world in general. They met on an African safari in 1972 and subsequently got married. He worked for the Smithsonian Institution for 17 years and has done films for National Geographic. She has degrees in zoology and physical anthropology and has done field work in South America and Southeast Asia.

They moved to Seattle in 1976, where the ideas for Adventure Travel publications were nurtured. Like those who caught the wind of the running craze, they seem to have been in the right place at the right time

"I really think we created an adventure travel gestalt in the minds of both the advertising people and the general public," says Citron, adding that the commercial organizers of the adventure tours described in his book are doing quite well, too.

"The earth is a fabulous place to live in the second half of the 20th century," he says. "You can still do all the things that the great explorers did and a lot more. Today there are incredible opportunities that average people can take advantage of if they have a few thousands dollars, or even if they don't."

Citron cites several reasons for the upswing in adventure travel. First, he says, it's cheaper to fly today in terms of real dollars than it was in the past. Air fares as a percentage of disposable income have actually dropped. Second, he says, "people are more curious and want to seek out the unusual. They are searching for ways to satisfy urges they've only been able to satisfy intellectually in the past." This, he says, combines with a growing need among some people to test themselves with the challenges of physical and emotional stress, and thus is linked to the whole physical fitness craze.

If you'd like a copy of the Adventure TravelGuide, it costs $9.95 plus $1 for postage. Write American Adventures Association, Suite 301, 444 NE Ravenna Blvd., Seattle, Wash. 98115. The 1981 guide will be out in December. If you're contemplating that purchase, you should also check out Fodor's "Outdoors America," which costs the same amount.

Meanwhile, if you just don't want to spend the money, here are a few of the 3,000 trips from a few of the 50 states and 114 countries: Ballooning

Over the Great Smokies on the border of Tennessee and North Carolina. The two-hour flights start at Gatlinburg, Tenn., with a maximum of four riders. June through September. Cost: $260 for four persons. Contact: Balloon Safaris, Route 6, English Mountain, Sevierville, Tenn. 37862. Dog Sledding

Explore Mt. McKinley National Park in Alaska by dog sled, skis and snowshoes. "People as well as huskies require stamina and coordination to maintain the pace," says the book. November to April. Cost: $100 a day, which includes cabins or heated tents, dog teams and guide. Contact: Denali Dog Tours and Wilderness Freighters, Box 1, McKinley Park, Alaska 99755. Mountaineering

Seven and 14-day trips for beginners and intermediates who want to climb three Mexican peaks: Orizaba, Ixtaccihuatl and Popocatepetl. Moderate routes, most camps in huts. November through March. Cost: $290 a week, including transportation in Mexico, accommodations, food, equipment and guide-instructors. Contact: North Cascades Alphine School, 1212 24th "G," Bellingham, Wash. 98225. Diving

On a private island, 15 miles off the coast of Belize in Central America.

Water temperature over 80 degrees; visibility 200 feet; diving accommodations at water's edge. Ear-round. Cost: $670 from Little Rock, Ark., for an eight-day stay, including transportation, meals, accommodations, tanks, weights, boats, all diving. Contact: Cap'n Frgos of Arkansas, 11401 Rodney Parham, Little Rock, Ark. 72212. Wilderness Survival

Eighty hours of instruction in eight-day cross-country skiiing and winter survival camp in central Colorado, with a base camp in Tennessee Pass. Learn winter survival techniques for university credit. In January. Cost: $178, including instructors and special equipment. Windjamming

Sail the Virgin Islands for eight days aboard a skippered windjammer embarking from St. Thomas. Snorkeling, exploring islands and shipwrecks. Year-round. Cost: $275 to $315, including meals and on-board accommodations. Contact: Westindianman Cruises, St. Thomas, V.I. 00801.