A Braver, Newer World for Adventure Travelers : Tour outfitters are striving to meet the demand for exotic trips. One example: simulated jet-fighter combat.

Adventure-seekers suffering from a frustrating case of the BTDT’s (Been There, Done That) can take heart. Ever vigilant for fresh offerings to lure customers, travel outfitters are debuting a bounty of new trips this year, and there may be something to please even the most jaded globe trekker.

What’s new out there?

How about a three-hour course in air combat, culminating in an actual aerial dogfight at 250 m.p.h. in a fighter plane? Or a 25-day cruise aboard a Russian icebreaker completing the first circumnavigation of Greenland? Or what about a day of “body-rafting” down a surging river that runs through Puerto Rico’s huge Rio Camuy caves? Or inn-to-inn hiking and biking in Ecuador with shopping at colorful markets and bathing in steamy hot springs?

“There’s a constant demand for something ever more extreme and remote that tops last year’s toughest trip,” said Richard Bangs, co-owner of Mountain Travel/Sobek in El Cerrito, Calif. Bangs was speaking over the din at the recent International Adventure Travel Show in Chicago, where potential customers sought details about mountain climbing excursions, raft trips and treks through some of the world’s coldest, hottest, lushest, and most barren regions. At the same time, Bangs added, “increasing numbers of clients want soft adventure experiences where the adventure comes to you, and you have a bed and sheets and plenty of hot water when you want it.”

For example, Bangs said Mountain Travel/Sobek’s most popular trip this year is its 17-day Antarctica excursion aboard a 38-passenger Russian research vessel ($4,750 plus air fare) where “the most athletic thing people have to do is get in and out of the inflatable exploration boats and walk around penguins.”

What about vacationers who want an athletic experience with all (or more than) the comforts of home? MountainFit, a San Francisco company, operates week-long fitness programs in California, Hawaii, Utah, Washington and Montana. Based at a luxury lodge or estate house, guests engage in rigorous organized hikes each day and return to massages, yoga classes, Jacuzzis, and gourmet meals provided by the MountainFit staff--kind of a traveling spa. Price: about $2,000 plus air fare. MountainFit, (800) 926-5700.

Along similar lines, Far Horizons, a Highland Park, Ill., company has organized an 11-day package to Israel that combines adventure travel (rafting, mountain climbing, and desert treks by camel, horse and off-road vehicle) with spa visits and stays in luxury accommodations. Price: about $2,400 plus air fare. Far Horizons, (800) 878-5344.

For families, the Angels Camp-based Oars rafting company is introducing 5- and 6-day floats down Idaho’s Salmon River with accommodations in rustic lodges along the route instead of the usual riverbank campsites. Children must be at least 4 years old. Price: $1,100-$1,300, plus air fare. Oars, (209) 736-4677.

Most arduous excursions require substantial physical endurance and dexterity, but Wilderness Inquiry, a nonprofit Minnesota company, organizes adventure trips for the disabled and able-bodied alike. Each excursion is about 50/50 disabled (including mental and physical handicaps) and able-bodied. These are not soft trips; they’re heavy duty treks, canoe adventures and dog-sledding excursions. Disabled people sometimes are paired to take advantage of individual strengths. For example, on a forest trek a wheelchair-bound woman with little force in her arms was teamed with a woman suffering from cerebral palsy, who had strength to push the wheelchair and needed the balance of the chair for stability. During a slide show at the Chicago adventure travel show, Tracy Fredin, the organization’s outreach director, showed a participant rappelling down a mountain--in a wheelchair! Wilderness Inquiry, (800) 728-0719.

While many travelers take a vacation for excitement or escape, an increasing number seek cultural enrichment or an opportunity to give of themselves in some way. A recent poll by Louis Harris and Associates determined that more than 80% of frequent leisure travelers surveyed rated cultural and historical themes much higher than night life, luxury resorts and shopping.

Myths and Mountains, a Pennsylvania outfitter that runs treks around the world, is helping to build village libraries in Nepal with funding from trekkers. The company’s owners were teachers before they began leading trips 10 years ago, and all excursions have a cultural/environmental focus, whether studying rain forest ecology in Ecuador or exploring religious life in Nepal. Myths and Mountains, (215) 896-7780.

The Sierra Club (415-923-5522) and Earthwatch (800-776-0188) were created to preserve the environment, and both run dozens of new trips each year where participants pitch in to clean up park lands or monitor endangered wildlife habitats.

Not everyone, of course, is of the do-gooder ilk. For folks who just want to go out and kill something, Fighter Pilots U.S.A. has just the ticket. For about $600, you get a four-hour course in air combat at the Kissimmee (Fla.) Municipal Airport (just down the road from Orlando’s Walt Disney World), which culminates in an airborne dogfight. You’re issued a flight suit, helmet and parachute (which, hopefully, you won’t need), given a blackboard briefing by a genuine F-16 pilot, then taken aloft alongside your pilot for aerial combat in an Italian Marchetti SF260 fighter plane. Actually, two planes go up, flying in formation at first, then separating for the “dogfight.” No flight experience is necessary, as the pilot does the actual flying. However, you get to “shoot down” the enemy aircraft: A tracking system confirms your “kill,” causing smoke to trail from your opponent’s plane. Then you turn around and the other guy (who, after all, also paid $600) gets to chase you and blow you away. Back on the ground, you watch your heroics on a take-home videotape, get your picture taken with your host pilot, are awarded a Top Gun Certificate, and, swears marketing manager Lee Abernethy, “go home looking exactly like Tom Cruise.” Fighter Pilots U.S.A., (800) 568-6748.

Following are other innovative adventure trips:

* A 17-day flying safari through Tanzania and Kenya, using twin engine, 10- and 16-seater planes, as well as four-wheel-drive vehicles stationed at landing sites. The planes eliminate long van rides along the often gutted roads be tween game reserves, and give participants access to remote, less touristed sections of wild animal habitats. Price: $7,300. Big Five Tours, (800) 445-7002.

* A 13-day raft trip on the Firth River, which flows through Alaska’s eastern Brooks Range to the Arctic Ocean, with views of arctic wildlife, including caribou, tundra grizzly bears, musk oxen and a variety of arctic waterfowl. Departures: June 20, July 18, Aug. 1. Price: $2,600 plus air fare. Mountain Travel/Sobek, (800) 227-2384.

* Mountain Travel/Sobek also is participating in the first circumnavigation of Greenland, the world’s largest island, aboard the Russian icebreaker, Kapitan Khlebnikov. The cruise takes in views of arctic wildlife, including polar bears, walrus, seals and numerous sea birds, and participants visit Eskimo communities and villages along the coast. Included are helicopter flights over Greenland’s coast to the ice cap, fiords and glaciers. The 27-day trip departs August 23. Price: about $20,000.

* The first adventure excursion through Vietnam. Several companies visit the country, but this trip, run by a seasoned Massachusetts outfitter, is more physical than others. The 23-day trips start in Bangkok, from which participants fly to the Vietnamese capital of Hanoi. The trip includes a three-day trek in the highlands west of Hanoi near the Laotian border, with home-stays in villages along the route; a day-long sail in a traditional wooden junk boat on Halong Bay; an overnight train ride to Nha Trang, plus explorations in the ancient capital of Hue and modern Ho Chi Minh City (Saigon), including the famous tunnels at Cu Chi. Next Departure is April 3. There is a hiatus during the long rainy season, April to October, then departures monthly, November to April. Price: $4,000 plus air fare to Bangkok. Overseas Adventure Travel, (800) 221-0814.

* Two- and three-day sea kayaking nature tours in the Matlacha Pass Aquatic Reserve off Little Pine Island in southwestern Florida, with moonlit kayaking and camping on tiny islands or at a local inn. Price: $95 to $125 per person per night including kayak and food. Gulf Coast Kayak, (813) 283-1125.

* Three-day sea kayak tours out of Phuket Island off Thailand’s west coast, with camping on small islands. Calm waters and excursions to uncrowded parts of this popular tourist resort island make this a good side trip from Bangkok. Price: $350 plus all air fares. A longer seven-day tour includes sightseeing in Bangkok, some hotel stays and air transfer to Phuket and back. Price: $1,100 plus air fare to Bangkok. New World Expeditions, (800) 878-2038.

* Week-long hiking, cycling or horseback riding trips around Ireland, with stays in inns and hotels. Trips range from easy walks on flat terrain to arduous treks, hilly cycling and extensive horse rides. Price: $750-$1,300, plus air fare (and meals on some trips). Destination Ireland, (800) 832-1848.

* A day-long “body-rafting” excursion through the subterranean river system of the huge Rio Camuy caves in northwestern Puerto Rico. Half hiking, half floating (wearing a life vest and helmet with lantern), the trip begins with a two-hour drive from San Juan. Excursions can be extended with camping inside or outside the caves. Departs Saturday and Sunday. A warning: This trip is very rugged, with strenuous hiking and caves containing some 20 varieties of bats. Price: $60-$80 (more for overnight trips), depending on group size. Arrangements must be booked well in advance. Tropix, (800) 582-0613.