WE FLEW away from Australia across the Tasman Sea to Auckland, North Island, one of the two islands of New Zealand that were isolated in prehistoric time from other land masses. The city, set on the Hauraki Gulf and built on the lava and craters of 50 extinct volcanoes, seems to pinch the top of North Island into two parts. In its harbor is the symetrical and graceful Rangitoto, youngest and largest of the extinct volcanoes.

Irritation with some group members' demands for rooms with views and complaints about playing radios too loud or too soft were forgotten in Auckland. There we had mail call and welcomed the return to the tour of the member left behind in Fiji, who had medical permission to rejoin us.

A must drive is the trip to the top of Mt. Eden in the city center. That extinct volcano has a fortified Maori pa (village) on its slopes and offers a panoramic view of the gulf, the two harbors, Waitemata and Manukau, and the sweep of the 95 suburbs of the city.

Also visible is One Tree Hill with its lone tree and lighted obelisk honoring the Maoris, the adventurous Polynesians who arrived in 1350 bringing rats and cats and managed to establish a culture of their own, long before the arrival of the Dutch and later the English.

The War Memorial, always gleaming white, sits high in the Domain, the public gardens. We visited it on a day with blowing winds, somehow fitting to view war, whether Arlington, Anzio, Normandy or Auckland. The Museum contains the culture of the people of the South Pacific, the history of New Zealand with a large display of flora, fauna and natural resources, and a Maori section. On the top floor is a "Hall of Memories" for the war dead.

At Warkworth is the New Zealand Satellite Tracking Station where a 100 foot-diameter dish contacts the satellite 22,000 miles above the ocean at the Equator. Outside Warkworth we boarded a ferry in the Hauraki Gulf for Kawan Island, a wildlife sanctuary. The mansion, home of an early governor, Sir George Gray, had been a vacation hotel, but the company pulled out, leaving the park service to worry over its maintenance.

The range service maintains the lovely sanctuary, haven for the fantall, tui and bower birds, wallabies and an abandoned copper mine. Someone said Australia had been marsupials, but New Zealand was birds.

And trees. We stared at two ancient kauris, named McKinley and Simpson, 800 and 600 years old respectively, and second only to the redwoods in age. It is illegal in New Zealand to cut the umbrella-top, hardwood tree. Handicrafts of the wood are made from dropped branches or natural falls. Lining the road was the punga or tree fern, also the national emblem.

Dr. Graham Meadows is the director of the Auckland Zoo, set on 35 acres. A veterinary medicine graduate, he is the only professional on the staff. He says he would like to see industry sponsor exhibits in the zoo. His appeal for funds each year is turned down, thus making it difficult to renovate and improve the zoo, he said.

The zoo had a superb Kiwi House with a nocturnal setting for the flightless bird. The female lays two or three eggs, disproportionate to its size, that the male incubates for 75 days. Other birds were the Kakapo, a sturdy brown flightless bird, the bronze Kea, "either a sheep killer or a gorgeous bird," but still a noisy hawky parrot, and the Takahe, until 1948 considered extinct.

Meadows told us that Kiwi research is difficult as only the injured or the lost end up at the zoo. The bird is protected as an endangered species. As in Australia, the New Zealand zoo had a strong education program with one leader working with 45,000 children. Since New Zealand wildlife is disease free, it is illegal to import ruminants or birds, thus limiting the zoo in its acquisition program.

A drive through sheep and cattle country, following the Wailkato River to the center of North Island, ended at Whakarewarea, a place of thermal activity with mud pools and geysers, the background for a Maori village.

The Waitomo Caves are famous for a grotto lit by the blue-green glow produced by thousands of tiny glow worms. The grub has a "lamp" at its rear and makes a silken wen of threads that act as fish lines for food and as suspension for its nest. It is sensitive to light and noise and, if disturbed, turns off its lights and rolls up its thread.

One of the most delightful days for the group was the visit to Hamurana Springs. We walked along streams, pitched coins in a deep pool, walked under giant redwood trees, watched fish and ducks and listened to birds.

Tour members had become friends. We later visited the Agrodome, a permanent exhibition building for the history of farming, to watch 19 prize rams that had performed in Japan, a shearing demonstration and two sheep dogs working stock in the pasture. It was a long and leisurely drive from Rotorus to Auckland and our department for Tahiti.

We said goodbye to our guide of five days, a man who loved his country, admired the Maoris and knew their language, and wanted each visitor to return to New Zealand some day. We had eaten beef, lamb, vension, guines, scallops and desserts. Shoppers had acquired nephrite jade jewelry, sheep-skin rugs, Maori carvings, paua shall ornaments and postage stamps.

It was morning when we arrived in Tahiti, French Polynesia. Schoolchildren waited for open-sided buses, venders sold fish on sticks and the commercial town was stretching. We spent three days outside Papeete in a hotel with each row of its balconies set back from the other to create the appearance of a fortress on the green hill.

The highlight of the stay on the mountainous island was a visit to the Gauguin Museum at Papeari. Only two of his original paintings remain on the island, but on a wall are postcard size reproductions of all his work, indicating where they are to be found - France, the United States, Russia and with private collectors.

The circle tour of the island provided a glimpse of the lure for the long-dead painter and for the countless waves of tourists of all nationalities who have ignored high prices and the constant intrusions on the lovely setting by luxury hotels and apartments.

We sat in one more airport waiting - but this time we were going home, going "up above" to Washington, D.C.

Group tours? Had we got what the FONZ brochure promised for $2,700? We think so. It is an advantage having two meals a day arranged; ours were all above-average. We flew on five airlines. The minibus in Fiji and open-sided bus in Tahiti had to be classed as "different and fun." In Australia, there were excellent bus tours with competent guides. In New Zealand we had a superior guide with a similar bus.

Hotels were nearer first-class than "deluxe," but notable for the cheerful service. It was great forgetting the baggage, climbing on a bus and being delivered to the hotel, room assignments completed. There was just enough free time in scheduled touring for each tour member to pursue specialized interests, such as museums, shopping, visiting friends.

When we compared notes with other group tours, our zoo visits were their envy. Their tour arrangements did not allow time of such interests. Would we go again? We're waiting for the postman to ring.