A trip to a set of islands off the coast of Queensland adds up to a magical combination of sea and sky - especially, finds Alex Finer, when you are aboard a historic red-sailed wooden schooner

We were a motley bunch assembled on the quay at Abel Point harbour in the midday sun: a middle-aged English family with two teenage children, a pair of young honeymooners from Nottingham, a Dutch couple with towering backpacks, an Italian rugby player, an English gap-year student, a schoolteacher from the Isle of Man, an astronomer from Oxford, and me.

We were a motley bunch assembled on the quay at Abel Point harbour in the midday sun: a middle-aged English family with two teenage children, a pair of young honeymooners from Nottingham, a Dutch couple with towering backpacks, an Italian rugby player, an English gap-year student, a schoolteacher from the Isle of Man, an astronomer from Oxford, and me.

Our separate journeys in Australia were about to become entwined; we were all passengers on a three-night adventure with Barefoot Cruises off the coast of Queensland. The plan was to sail between some of the northern Whitsunday islands, spending one night moored on the Great Barrier Reef.

We began to bond, exchanging smiles, the moment we met the captain. He arrived with a sulphur-crested cockatoo called Seedbreath. What more could we want than a captain with a parrot? And the sense of excitement grew as we caught our first sight of the vessel that was to carry us to sea. The Coral Trekker is a 23-metre, square-rigged, wooden schooner with rusty red sails, built in Norway in 1939.

With some surprise, I calculated that Lt James Cook first charted these waters less than four times as long ago, aboard a wooden, square-rigged vessel, the barque Endeavour. His mission had been to observe the transit of Venus at Tahiti and then to explore further south. Arriving here on what he believed to be 3 June, 1770, and Whit Sunday, he dubbed the channel off the mainland the Whitsunday Passage and named the islands the Cumberlands after the younger brother of his benefactor, George III. Of the 93 islands and islets now better known as the Whitsundays, only a handful are inhabited.

As we left harbour on a glassy flat sea, under power, Captain Mark Bresman rang the ship's bell twice and explained the rules. One clang would mean food, two clangs information and three clangs abandon ship. He pointed to the inflatable lifeboat stowed on deck. The most likely threats to our well-being, he hammered home, came from failing either to put on sunscreen or to get cuts and grazes washed and disinfected immediately. Problems with sharks, stingrays, stonefish and cone shells were rare and, fortunately, it was not the season for box or irukandji jellyfish.

Then the thrills took over. With the mainland still in view, we saw a humpback whale. The first sign was a spout of water. Then, after a long wait, cameras in hand, we saw more spouting, and a huge curved back rose and rolled, followed by a slow wave of the tail which came clear of the water before the creature disappeared again.

Off Black Island, a pair of osprey called to each other in the trees, caught fish and fed their young. We took to the dinghy with flippers and masks and landed on a small, sandy beach before exploring an outcrop of coral just offshore. Back on board, we began to adapt to the cramped facilities below deck: a couple of litres of cold water constituted a shower.

Night falls quickly in the tropics, and Caroline, a young New Zealander, was already busy in the galley preparing our evening meal. Drinks - rum and coke or gin and tonic in cans, as well as beer or wine - were served on deck by the other two crew, Kenny and James, as the stars of the Southern Cross appeared.

After dinner, eaten around the table in the wheelhouse, many of us lay on the deck, amazed at the brightness of the Milky Way. We stared at starlight that had travelled for millions of years, caught shooting stars in the corner of an eye, and contemplated the awesome presence of so many worlds.

"It's not an archer, it's a teapot," said the captain, pointing out Sagittarius in the confusingly crowded sky. When I finally traced the dots, I saw the Michelin man and not a teapot. Isobel, the astronomer from Oxford, felt unable to arbitrate. Conversation turned to black holes and the expanding universe.

I was topside to see the sun climb over Hook Island the next morning. It warmed the deck, brightened the sky, poured colour and sharp shadows over the neighbouring islands, adding ripples to the pewter sea. A swallow-tailed bird with a red chest rested briefly on the boat while the captain listened intently to the crackling weather forecast over the ship's radio.

Our first port of call after breakfast was Luncheon Bay, to marvel at the coral thrown back by cyclones into a gully behind the sandy beach. And then came a rendezvous with a dive boat. Both experienced and first-time divers enjoyed going 10 metres down to join the tropical fish, anemones and sponges on the coral. But the best was still to come: Bait Reef, 16 nautical miles further out to sea, and part of the Great Barrier Reef. "Not a comfortable overnight location except in exceptionally calm conditions," says David Colfelt, the author of 100 Magic Miles, an indispensable guide to the region.

Our luck was in. Not only were we able to moor without problems, but we enjoyed 15-metre visibility beneath the surface, snorkelling around the Stepping Stones - a unique series of flat-topped coral pinnacles - exploring forests of soft corals and gorgonian fans. We looked for the clown fish (known as Nemo since the animated Disney movie) that lives among the poisonous tentacles of the anemone. We found, instead, a turtle threading its way through wonderland.

That night, the captain displayed a penchant for poetry, with a rendition of Marriott Edgar's The Lion and Albert. He sang shanties, accompanying himself on a small squeeze-box. The teacher from the Isle of Man responded with a jig played on her penny whistle.

Morning brought a change. The wind had swung from north to south and freshened. There was an urgent chatter to the sea as it chased past the boat. The radio talked of a Force 5. And at last the rusty red sails were rising up the masts, with much co-ordinated manpower tugging at the ropes that raised them.

The Coral Trekker ploughed a steady path through the choppy waters all morning. I took a turn at the wheel, keeping course by compass and with an eye on the headland we had to pass to reach calmer waters. After halting to watch a pair of whales, and to snorkel off the low-tide sandbar extension to Langford Island, we sailed on, escorted some of the way by dolphins. We dropped anchor for the last night at South Molle Island.

Supper and stars, bed and breakfast: our journey was drawing to a close. Already growing nostalgic, Richard, Jan, Chris, Sarah, Steve, Rachel, Mark, Maia, Max, John, Isobel, Ruth and I went ashore for one last quick adventure - the walk through a blizzard of blue butterflies, past fruit bats and beneath chattering parrots to the lookout point at Spion Kop. Then a last cup of tea and a splash off the boat. Docking at Shute Harbour on the mainland, we swapped email addresses, and cameras were handed to shore for countless group photos.

Some of the party were bound for Airlie Beach, just up the road. It offers accommodation ranging from backpacker hostels to the comfortable Coral Sea Hotel with its small jetty, watersports and commanding views.

The family on board were off to Hamilton Island, a high-rise holiday camp property with its own airport. The honey- mooners were going to enjoy a luxurious break at Peppers Palm Bay on Long Island, reached by catamaran from Jilly's ferry terminal.

Others were heading south to Brisbane or to Sydney from the airport at Proserpine. I went north to the Daintree where Queensland's rainforest meets the Great Barrier Reef.

But all of us, I think, envied Max, the Italian rugby player. He was heading back out with Coral Trekker for another three days of Whitsunday wonder.


How to get there

The author was a guest of Austravel (0870-166 2070; www.austravel.com). It offers a seven-night Whitsunday Cruise from £1,319 per person, based on two sharing, with flights and all-inclusive seven-day cruise.

Where to find out more

Queensland Tourism ( www.queenslandholidays.co.uk). Tourism Australia (090-686 33235; www.australia.com).