Skiing in August? That's one way to get fit for the American ski season. But where?

Anywhere in the Southern Hemisphere will do: Our summer is their winter. The peaks of Chile or Argentina were possibilities. Then I learned about New Zealand: one of the off-season training grounds for the world's Olympic ski teams, with 230 mountains more than 7,500 feet high and 400 glaciers providing varied, nearly virgin ski country.

So how does a duffer like me -- a terminal intermediate skier -- end up on top of New Zealand's Mount Roy drinking champagne as dawn douses the surrounding icy summits in pink? I simply joined 21 other summer skiers on a three-week ski-and-snorkel adventure in the South Pacific.

The first two weeks of our trip would be work -- early mornings, such as this, and hard skiing. The reward was a final week on the warm beaches of Fiji.

The morning had begun at 5 a.m. at our hotel on Lake Wanaka, on New Zealand's South Island. In the dark, we were escorted over to one of New Zealand's inevitable sheep pastures (at latest count, the country has 80 million sheep and 3.3 million people). There we were picked up by a helicopter that carried us to the top of Mount Roy, first skied by mortals in 1984.

New Zealand mountains are young, and the jagged South Island skyline looked razor sharp. Watching the morning sun light up the Kiwi equivalent of the Matterhorn -- the 10,000-foot Mount Aspiring -- I began to wonder, "Can I snowplow down?"

Picture yourself standing in the airport in August in sneakers -- with a bathing cap, parka, skis and poles under one arm and a net bag with flippers, hiking boots and a diving mask on the other. You look like someone who has an identity crisis. Of course, this is also how you recognize other members of your group.

Our group last summer consisted of 15 vacationers (two married couples, eight other men, three other women) plus three coaches and their wives. In age, they ranged from 67 (with asthma) to 17 (without). In skiing ability they were advanced intermediate to expert, with one exception -- me. My style is best described as a flying wedge or frozen snowplow. But our guide, Steve Bounous, had a pro's credentials: former U.S. Ski Team member, World Cup pro and coach at Utah's Snowbird resort.

Our flight from Los Angeles to New Zealand landed us in Christchurch, on the east coast of the South Island, after about 16 hours and 6,865 miles. Despite stops in Honolulu and Nadi, the flight can seem like one long dinner party unless you rigorously demarcate the meals, like a prisoner with blocks of days scratched off on his cell wall.

Our base camp was at Lake Wanaka, about a five-hour, 360-mile drive southwest from Christchurch -- with a stop for lamb burgers along the way. Wanaka is still one of New Zealand's undiscovered ski areas and one of the few with overnight facilities.

The New Zealand landscape, varying from tropical to highland rugged, is constantly surprising. It's hard to get used to a snow line -- starting at 1,000 feet -- spattered with tikouka, a cabbage palm (named by British explorer Capt. James Cook, who thought its leaves tasted like cabbage). On the mountain at Wanaka, you look out over a sparkling, trout-filled lake to the brown and green of sheep pastures below.

Even more incongruous in a snowy ski world is the dark green kea, a parrot-like bird that alternately flies -- displaying a bright orange wingspread -- walks, hops and screeches among the skiers, snatching sandwiches and picking apart backpacks.

That first morning, a couple of runs down Mount Roy were followed by a shower and breakfast, and another dash to another sheep pasture, the unpaved runway of Aspiring Airlines. There we boarded assorted Cessnas, taking off in a hail storm of sheep droppings and flying over mountain ridges and lime-white glaciers pushing between peaks down into rain-forest fiords. An hour and a half later our planes landed amid seagulls swooping down from all directions into Milford Sound. A bus carried us to a launch. We lunched on lobster and champagne and swatted at an occasional sand fly, as we marveled at the lolling fur seals and 6,000-foot Mitre Peak.

The small-plane and helicopter rides were firsts for me, and another first was skiing off a beach. One dawn we were loaded into a launch and ferried across Lake Wanaka to another mountain range. Once ashore on the pebbly beach, we were taken by helicopter to ski the day in the Buchanan Mountains (verticals between 3,000 and 4,000 feet). But not until we had all been equipped with transmitters around our necks and instructed in the cross-hatch walking pattern of hide-and-seek, in case we ended up on the wrong side of an avalanche: under it.

Lunch was flown in, and eventually we were all helicoptered back to the beach, to the customary upbeat cockpit music tapes -- "Victory at Sea" -- for a bonfire and drinks.

Our last day on the slopes, we scrambled into vans with all our luggage and headed for Mount Cook, hoping to catch ski planes for a 20-minute flight to the Fox and Tasman glaciers. But the weather once again closed in, so we had to opt for hiking, heli-skiing on other ranges or a flight tour of the area. We spent a windy night at Mount Cook's famed Hermitage Hotel.

After six hours on the road to Christchurch, at times stuck behind border collies intent on herding a grumpy ram or stray ewes right down the middle of the highway, plus another five hours in the air, we left the blustery peaks of New Zealand and landed in the bright green of Fiji.

We stored our ski gear for a week at a hotel at Nadi (pronounced "Nandi") Airport and settled there for an overnight stay. The next morning we were airborne over little strings of islands floating in light and dark blue seas, headed for the island of Vanua Levu and the Namale Plantation.

Namale is a 125-acre working copra (coconut oil) dude plantation. We stayed in modernized native thatched-roof bures, which were equipped with baths and fans. Each bure was secluded, surrounded by palms, frangipani, mango trees and hibiscus. The gourmet food served at the main plantation house included fresh fish and such new tastes as breadfruit fries and rou rou soup (made from a deep green leaf that tastes stronger than spinach).

What a contrast. We had traded the regimentation of ski camp for tropical days of wind-surfing lessons and fishing trips. The thud of ripe coconuts on thatch-like lawns replaced the similar sound made by skiers tumbling on the slopes.

Sailboats were available. So were speedboats or powerboats ($18 to $25 per hour). Cars could be rented for a drive into town or across the island. We also had a chance to take a jungle hike up to Namale's water supply: a mountain waterfall. We played tennis in the early morning or around 5 in the afternoon, when harmless fruit bats started winging across the sky and the Fijians let down the mosquito netting over our beds.

But the best sports of all were underwater: miles and miles of snorkeling and scuba diving (Namale's equipment is state of the art). We merely had to walk out of our bures, which were situated with the rest of the plantation buildings on a bluff above the mouth of a lagoon, and then down to the sea, where a flat coral reef extends 300 feet from the shore.

When I returned home from my three weeks at winter/summer camp, towing my gear for all seasons, I looked just as silly as when I had left. In the deep heat of the Washington summer, I was primed for the slopes.

N.A. Straight is the author of the novel "Ariabella: The First" and is currently finishing a biography of Sen. Thomas Pryor Gore of Oklahoma. WAYS & MEANS

Our trip was sponsored by Bounous International Ski Adventures, which this year is offering two ski-and-snorkel vacation packages, each limited to about 22 persons. The first session started July 26. The second session offers two weeks of skiing in New Zealand and an optional five days on the Tahitian island of Bora Bora. Dates are Aug. 19-Sept. 4 for New Zealand only and Aug. 19-Sept. 9 if you go to both New Zealand and Bora Bora.

The cost is $4,350 ($3,550 for New Zealand only), which includes round-trip coach air fare from Los Angeles, double accommodations, lift passes, all coaching, transportation, training facilities, as well as a river run on a jet boat and a Hovercraft tour in New Zealand. Meals are included in New Zealand but not in Bora Bora. Heli-skiing and glacier skiing cost about $175 more a day. INFORMATION: Bounous International Ski Adventures, 1153 E. Windy Peak Circle, Sandy, Utah 84070, (801) 572-6437.

For general information about skiing in New Zealand, contact the New Zealand Tourist and Publicity Office, Suite 530, 630 Fifth Ave., New York, N.Y. 10111, (212) 698-4680.