I'VE JUST lost a week from my summer by flying into the middle of winter by accident. What they say turns out to be true: in New Zealand things really are upside down. This means you can eat your Christmas turkey on the beach but it also means you can spend a week of your summer vacation huddled by the fire. Can you imagine anything more disorienting?

There's a stiff, grey wind blowing into Wellington this morning from somewhere in the vicinity of the Antarctic. Snow-covered volcanoes are brewing on the horizon. I'm wet and cold and ready to believe that I have made a huge mistake.

The other problem is the time of day. The difference between New Zealand time and Greenwich Mean Time is a round 12 hours (leaving aside the one hour of British Summertime). In a sense, things could not be more convenient: you do not have to move your watch-hands at all. You merely have to declare to yourself that it is, in fact, dinner-time not breakfast-time. In practice, the strain of eating buttered toast every day for dinner and lamb shanks and seared tamarillos with wine for breakfast can get you down.

Not that I have anything to complain about. It's the people who fly from Los Angeles to New Zealand who really have grounds to be confused. Say your plane leaves LA on Saturday evening, it will arrive in New Zealand twelve hours later the next day in the morning - Sunday morning, you suppose. Except that, in fact, it will be Monday morning. You will have crossed the International Dateline on the way across the Pacific and an entire Sunday will have vanished from your life forever.

Coming back will be equally disorienting. If you leave New Zealand early enough in the morning, you may have the pleasure of arriving in Los Angeles on the previous day in the evening.

No wonder people want to go bungee jumping in this country. International tourists to New Zealand need the correction in perspective that only hanging upside down from a piece of elastic can give you.

Yes, the pavements are stained wet in Wellington and umbrellas blow inside out, just like in (say) England. And yes, people also seem to speak English here. But other things are grotesquely unfamiliar. Spiky green leaves, dangling tendrils and scaly pods drip rain from every tree and shrub. Purple flowers with giant flabby petals quiver under the weight of dew. It is cold here (honest!) but to judge by the flora you have to wonder whether it ought to be the tropics.

Is New Zealand deliberately disorienting? I have just been to the new national museum known as Te Papa, in search of answers to the problem. Maori carvings, Kiwi fruit, The Rainbow Warrior, the All Blacks, earthquakes and the world's biggest insects all feature, as do simulated bungee jumps, in which the participant is held upside down in a cage by the ankles. Queen Elizabeth II (whose head still appears on New Zealand coins) and the Union Jack are never far away either.

But the section on New Zealand's immigrants is the most enlightening. I saw an interview with a Hungarian who had sneaked across the iron curtain in the snow; an Indian who had landed in a flying boat; an orphan who had come in a cattle-ship from Iraq. Unlike today's international tourists, these people had bigger things to worry about than losing a week of their summer holidays.

When they arrived by ship in the 1950s they first glimpsed New Zealand on the horizon as a country covered in grey boulders. Then they came nearer, saw the boulders move and realised they were sheep. There's disorientation for you.