The flying aluminium pencil case that carries you slowly to Tonga's outlying island groups is a neat metaphor for the Pacific's only remaining kingdom.
You climb on board, using a steep staircase, feeling that the romance of travel is alive and well, even if you are wearing a sarong, T-shirt and jandals, and not a smart suit, brogues and a hat.
Then you puff up the considerable slope the DC-3 is resting at to reach your seat and look back at its solid, dumpy body shining in the sun. It's out of date, not very flash, certainly not very quick. But the folks are very friendly and it's an exhilarating ride on a time capsule chugging through space.
The Kingdom of Tonga is a bit like that. Protected, for the most part, from outlandish foreign development by its policy of leasing, not selling, land to outsiders, it's a tiny nation with enormous potential, but one that you can only hope will never get too big in tourism terms.
Tonga is whatever you want it to be: you can backpack or idle around in pampered luxury, but you'll never feel like the end product of a Pacific Island tourist sausage machine.
From Nuku'alofa, we are heading for the Vava'u group in a little piece of history. DC-3s, as well as travelling slowly, also cruise low - perfect for taking in the scenery offered by a flight over dozens of islands and coral atolls. We can see coconut palms swaying, rimmed by golden sand, then expanses of water darkening from turquoise to a deep, rich blue. And we spot buildings and villages, harbours and boats in the paradise below.
After an hour or so, we touch down on a funny little island airstrip where another DC-3 squats on the tarmac. I feel as if I'm part of a Tintin story, descending into a timeless jungle with my comic-book pals. But there is no Snowy, and the locals are saying "Malo e lelei" ("Welcome"), not "Billions of blue blistering barnacles".
The former is something you hear a lot. Tongans are delightful people. They are often rather shy towards visitors, but with no "colonial cringe" to feel even slightly resentful about, their friendliness seems genuine. (The young men, brought up to lead active, God-fearing lives, invariably look like bronzed Adonises. When my friend Gill comments that one we meet "makes Jonah look like a pencil-neck", she's not far wrong.)
We're in Neiafu, capital of the Vava'u Group, which is synonymous worldwide for top-class sailing. Neiafu is nestled in the Port of Refuge, where international yachts converge like migrating birds for much of the balmy year. As well as having the most breathtaking tropical island scenery, Vava'u is close to the Tongan Trench, one of the deepest troughs in the Pacific. This ensures a steady food supply for the world-beating marlin and other game fish regularly pulled out of the water here. The volumes of clear water the trench produces also makes for some of the best diving and snorkelling in the islands.
But for now, we're content to loll about at the Paradise International Hotel in Neiafu. It's known as a meeting place for yachties and landlubbers alike. In a wonderfully democratic way that accommodates everyone, you can do it on a budget or go all out for the luxury of a huge room decorated in a subtle "planter" style with its own balcony overlooking the harbour. There's a fine-dining restaurant by the pool.
In the afternoon, we travel around and meet Gisela and Matakaiongo, a German woman and her Tongan husband who have built a couple of fales (beachhouses) and named them after their dog, Lucky. Then we meet Dieter and Senikau, a German man and his Tongan wife who own the glorious Tongan Beach Resort on 'Utungake Island. In real estate terms, it's beachfront: a seductive enterprise with little bungalows right on Hikutamole Beach.
Day two in paradise is spent on the water, with ex-pat American Larry Schneider on his 11m trimaran, Orion. It's windy and we're soon skimming over the waves past uninhabited islands that look too picturesque to be real.
We're keen to see what's under the water. Anchoring near uninhabited 'Euakafa Island, we clamber into a rubber dinghy and travel a short distance to the reef. Schneider says it's too cold for him to go in without a wetsuit (it's November), but we leap overboard into the enormous warm bath that is the Pacific Ocean. Gill, who hasn't snorkelled in the islands before, is spellbound by what she sees. Coloured fish are everywhere. Shy creatures (a little like the locals) zip in all directions.
After half an hour, we're happy to be back in the dinghy and heading for a hot lunch of lentil stew and Tongan bread, washed down with tea. Then we return to 'Euakafa to trek to the high point of the island 100m past the tomb of Queen Talafaiva, who was murdered by her husband for committing adultery in ancient times. We walk through the rainforest along a track that is hard to make out in places. There are no other visitors, no Coke machines, no signs.
Back on the Orion, we have a fast trip back with the wind behind us. Schneider delivers us to his houseboat home, which is painted with a mural of Tongan village animals and dubbed the Ark Gallery. His wife Sheri makes and sells paintings and other artworks, aided and abetted by Castaway and Cheeto, two ocean-going cats, which, apparently, fret for the briny if they are away from home for too long.
We are whisked off to the Tongan Beach Resort to get a taste of the lying-on-a-deckchair-and-drinking-cocktails business, arriving in time for a cultural night with a buffet of delicious local food. Gill gets stuck into the kava, but I'm more interested in sticking Tongan banknotes on to the oiled bodies of the male dancers. The best of them end up looking like financial patchwork quilts.
Our last day on Vava'u is the best and the worst it can be. We go whalewatching, buoyed up by other guests' stories of how they have swum for hours alongside the majestic humpbacks and their little ones.
We join a group and head out in a large aluminium boat to track whatever pod is around, but it's windy and, after five hours, Tongan brothers Luli and Mika still haven't spotted so much as a waterspout.
Everyone is wet and disappointed. We're told this is only the second whale-free day all season. But, just as we head back towards the Port of Refuge, a call comes over the radio from another whalewatching group that has found a mother and calf. We head in their direction and wait until the group has seen enough. Soon we are following the pair at a respectful distance, realising that both can power away from us or choose to stay and check us out, too.
We are in choppy open water, but a group of five don snorkelling gear and ease into the water with Mika. They are back on board a few minutes later, and most didn't see the whales.
Then Gill and I take our turn. It's hard to know where to look, but Mika signals that they are below us. With my mask and snorkel on, I look down, trying to stop my gear from flooding. For a few brief seconds, I see an enormous pale shape, and a smaller one, about 10m below me. Then they are gone, and we get back on the boat.
I am at once exhilarated and crushed that I saw them, but the chance came and went in the time it takes to cry "Please don't leave yet".
So it's hard to listen to our fellow guests at the resort, who talk about their life-changing experiences with great pods of playful humpbacks that whacked them gently with their pectoral fins. One couple insists on showing us a DVD of their six days' swimming with them.
The next morning we are back on the flying pencil case. The visit has been too brief, but wonderful and different from anything I've done. As the DC-3 heaves itself off the ground, I look at the peaceful scene below. Soon, we are winging our way over ocean and I imagine that I can see pods of humpbacks cleaving their way through the water, or huge gamefish in pursuit of prey. Or even Castaway and Cheeto dozing on the deck of their houseboat.
* Diana Balham travelled to Tonga courtesy of Polynesian Airlines.
Polynesian Airlines flies to Tonga up to six times a week, out of Wellington and Auckland, from $411 return. Contact the airline at www.polynesianairlines.com or freephone 0800 800 993.
Peau Vava'u Airlines, which flies from Nuku'alofa to Vava'u, can be contacted on 00 676 77328.
The Paradise International Hotel, phone 00 676 70211, email email@example.com, website www.tongahost.com. Rooms are from $55, plus tax, a night.
The Tongan Beach Resort, phone/fax 00 676 70380, email firstname.lastname@example.org, website www.thetongan.com. Five-day packages including food are from $842 a person. ACTIVITIES Orion Charters, phone 00 676 70115. Charters are $33 per person a day, plus a light lunch.
WhaleWatch Vava'u, phone 00 676 70747, email email@example.com.