But we have our eyes fixed on the reef in front of us that appears, quite bizarrely, to be rising up out of the sea, its rocks emerging, dripping with water and sequinned with huge oyster shells. As we watch, an elegant osprey swoops to pick up a stranded fish in its talons. Perched on the rocks, huge shags stretch out their wings like cloaked magicians, and Caspian terns – monochromatic except for their fierce red beaks – patrol the skies for any other treasures gifted forth by the reef.

I’m in the Kimberley, one of Australia’s last great wilderness destinations, a place imbued with spine-tingling natural and human history, from frontier wars and tales of dangerous pearl diving to Aboriginal Dreamtime stories and millennia-old landscapes. This 20-mile reef – which ‘rises’ out of the water when the tide recedes – is just one of the staggering natural wonders the Kimberley offers and is the latest in a long line of eye-popping sights that we’ve already witnessed on our cruise.

Languishing in the far northern reaches of Western Australia, the Kimberley is double the size of the United Kingdom, but has fewer people per square metre than almost any other place on the planet. Its stunning coast is recognised as one of the world’s most pristine marine environments, and it is argued that the coral biodiversity and rich sea life here surpasses that of its far more famous east coast counterpart, the Great Barrier Reef.

However, I quickly discover that everything here is big and bold: the weather systems, with monsoonal rains thundering down in the wet season; and the colours – giant brushstrokes of amber, crimson and vermillion, which make it look as if someone has turned the saturation dial up to max.

A ship to remember

A 12-day cruise with Abercrombie & Kent is the very finest way to explore this otherworldly destination. Running from the old, storied pearling town of Broome to the busy port city of Darwin, it takes guests through remote, rarely visited landscapes that certainly have to be seen to be believed. The cruise is a perfect add-on for any Western Australia adventure, and many of the people I meet are pairing it with trips spent swimming with whale sharks in Ningaloo Reef, or food-and-wine sojourns in WA’s most spectacular gourmet region Margaret River, just three hours south of the capital city of Perth.

Our ship, the 184-capacity Le Lapérouse (a Ponant vessel chartered by A&K), is a brilliant base from which to explore the thousands of islands that speckle the Kimberley coastline. Luxury is the name of the game on board, with the ship’s 92 staterooms and suites offering private balconies and muted, elegant decor (all suites also come with personalised butler service).

When you’re not exploring the land for hidden Aboriginal rock art or snorkelling among sea turtles and velvety blue starfish, there’s a chance to relax at the Ponant Yacht Spa, or grab a glass of champagne and head below decks to the Blue Eye Lounge, an underwater viewing area that’s designed to look as if you have been swallowed by a whale. Unsurprisingly, the food on Le Lapérouse is impressive, too. Before we head out on our daily excursions, a buffet breakfast – a hearty feast of omelettes, eggs Benedict, pancakes, sausages, fruits and pastries – is served at Le Nautilus restaurant (with plenty of champagne for those who like to start their day among bubbles).

Lunches at Nemo restaurant on the aft deck, usually eaten amid excited conversation about the morning’s sightings, are a relaxed and delicious hybrid of buffet and ready-to-order dishes – think Wagyu beef burgers, barramundi stations and salads. Dinner, however, is a much fancier, table service affair. Under a glowing silvery moon on the outside tables at Le Nautilus, we tuck into lobster with celery remoulade and truffle dressing, and king fish fillet with zucchini and pea risotto, all paired with the finest Artémis Domaines wines.

High-end adventure

From the helicopter, the ocean below looks like a swathe of vast, unruffled silk – a vivid blue-green expanse that stretches wide as far as the eye can see. The islands, most of them entirely deserted, sway with lush, emerald vegetation. All around us, the sun beats down with a warm, syrupy glow, gilding the apple-green mangroves and tendrilous creeks with a metallic, ethereal sheen.

I almost pinch myself that these are the sorts of excursions included in our cruise. “There’s a croc!” I gesture excitedly out of the window, as an armoured creature glides slowly through the water, tail swaying. It all seems so out of this world, and when we land at the magnificent Mitchell Falls – seeing cliffs that harbour 60,000-year-old rock art, and knowing there’s little other life around, aside from the kites wheeling on the thermals and the king brown snakes sheltering in the crags – feels like a huge privilege.

Each day, our experienced expedition team – who have led trips all over the world, from Antarctica to the sunny South Pacific – shepherd us efficiently into helicopters and Zodiacs, taking us out to discover remarkable, rarely visited sights. At Horizontal Falls, where massive tidal movements create a waterfall that moves horizontally through craggy red cliffs, my eyes boggle at the sheer dramatics of mother nature (it’s no wonder David Attenborough once described it as one of the world’s greatest natural wonders).

At Ashmore Reef we witness a wildlife spectacle worthy of any Sunday night BBC documentary: an isolated island a few hundred metres long and just 20 metres wide teeming with hundreds of thousands of seabirds – fluffy frigate chicks on the nest, red-footed boobies and terns filling the skies.

Knowledge base

When we return from our activities, what we’ve seen is put into context with a nightly lecture series. As well as geology chats and amusing nature talks, anthropologist Dr Shirley Campbell helps us interpret the rock art we spotted out in the landscape. Yawuru guide Bart Pigram also speaks engagingly about Aboriginal history and his family’s links to pearl diving, illuminating how indigenous people were exploited in pursuit of the gleaming pearl shell that can be found in the waters of the Kimberley.

But ultimately, as with the very best trips, sometimes the most spectacular things happen when you’re doing very little at all. In the Kimberley, even whiling away an afternoon on your private balcony is an adventure, and it’s my very favourite thing to do aboard Le Lapérouse. Sometimes I stand, binoculars raised, scouring the waters for the huge Stokes’s sea snakes that occasionally drift past like damp noodles.

I watch as patches of seaweed pass with tiny fish sheltering underneath. Jellyfish float like transient clouds and sometimes dolphins flip their silver bodies in the sun as they chase balls of tuna.

It’s all a reminder of what a remarkable part of the world the Kimberley is, and as we gather with drinks and canapes each evening on the Observation Deck, and as the sun sinks into the horizon, flinging lilacs, golds and burning ambers across the sky, it feels like I have been let into one of the world’s greatest secrets. The Kimberley will have me in its thrall for a long time to come.

Book it: Abercrombie & Kent offers its 12-night A&K Expedition – Kimberley Cruise: Australia’s Last Frontier from £12,699 per person. The price is based on two people sharing and includes flights to Broome via Perth, transfers, excursions in Broome, activities on board and balcony accommodation. abercrombiekent.co.uk