Rearing up with its claws outstretched, the polar bear is poised. His white fur is soaked ruby red with fresh blood and he looks tired.

He lunges forward, sinking his 400 kilos onto the bloody carcass of a walrus. He pounds the body again and again, hungrily tearing at flesh and intestines.

It's not the meal of choice for polar bears, but as the ice sheet retreats and opportunities for seal hunting dwindle, these endangered creatures are getting desperate.

It's 3am in mid-July at a latitude of 79-degrees north. The sun, which last set three months ago, skims the horizon and casts long, spindly shadows across the deck of cruise vessel MS Expedition.

But we've been summoned out of bed for good reason: this is our first sighting of a polar bear.

Poster boys for an ailing planet, trapped in the grip of global warming, these violent but beautiful creatures are attracting an increasing number of adventure-seeking visitors to the Arctic region.

G Adventures, which owns the MS Expedition, operates cruises around Svalbard, an archipelago 650 kilometres north of mainland Europe that forms the gateway to the permanent ice sheets covering the North Pole.

Much of David Attenborough's Frozen Planet series was filmed here, and the chances of sighting polar bears are high.

Our cruise begins in Longyearbyen on the largest island Spitsbergen, one of three inhabited towns in Svalbard with a domestic airport connecting to Norway.

Sitting above the treeline, very little grows in this harsh and frigid environment, although – somewhat ironically – the world's seed bank is located here.

Unpredictable and unforgiving, the landscape is dominated by jagged glaciers and mountains forced up from the seabed with such pressure they resemble concertinas.

During summer, when temperatures can reach a balmy 13C thanks to the Gulf Stream, the ground is carpeted with moss, lichen and dainty flowers.

Snowmobiles, no longer needed until winter, are parked outside colourful houses on lawns filled with soft white pom-poms of Arctic cotton grass. But signs warning of polar bears are a reminder that danger is never far away, and it's not uncommon to see locals carrying rifles.

Unlike realms such as the Galapagos Islands, there are very few restrictions governing Svalbard. Cruises start and end in Longyearbyen, explains expedition leader Alex, in between is an open book.

A crew of experienced geologists, naturalists and biologists chase the receding pack ice in search of polar bears.

At the mercy of an ever-changing landscape, the boat is often forced into uncharted waters, making this one of the only places on earth where true expedition travel is still possible.

Hoping to manage our expectations, Alex warns there can be as many as three landings per day or as few as none.

"And don't assume there'll be close encounters," he says.

"Svalbard is about seeing animals in context."

Ahead of our visit to Magdalena Fjord, where pebble beaches are surrounded by tundra-covered mountains and glassy pools, armed scouts go ahead to check for bears. Yesterday a mother and her cubs were sighted here.

The beach is home to nesting Arctic terns, who are fiercely protective of their young. They dive-bomb our party, clacking their beaks in a round of machine gun fire, and are capable of drawing blood.

I sprint for safety past the ruins of a blubber oven, a reminder of the whaling industry that dominated this region in the 17th century. Once these waters were filled with belugas, unicorn-like narwhals and blue whales, four times larger than the biggest dinosaurs that walked the earth. But they were hunted almost to extinction.

It's unlikely they'll ever return to these waters again.

Last week, the crew spotted 22 of polar bears but it's day four and we've only seen one.

In search of ice – and bears – we're forced to head north into milky grey waters scattered with blue-tinged icebergs. Our ship grinds through sheets of ice, breaking them into pieces of a jigsaw puzzle that will never fit back together again.

As a thick sea fog descends, we sail further into white noise.

For two full days, we can't see or do anything.

The biggest challenge, however, is yet to come. While heading into uncharted waters, the boat hits sand.

After a frantic few hours, the captain announces no major damage has been done but we will have to cut short our trip and head back to Lonyearbeyn.

Fortunately, we're able to squeeze in a couple more landings.

On our final stop at the 14th July glacier, only patches of ice remain. On the beach is a polar bear and her cub.

She ventures towards the water's edge and raises her nose to catch any scents on the wind. A bearded seal lies on a piece of ice, like a sausage on a dinner plate, but the bear has other plans in mind. Scrambling over a mound of pebbles, her cub in tow, she disappears inland.

Being this far south, and far from fast ice, I'm left wondering whether the pair will make it through to next winter.

If it's tough to spot bears now, it's only going to get harder.

* The writer travelled on the 8-day Realm of the Polar Bear trip onboard G Adventures' MS Expedition. Prices around $A8100 for a single traveller and $A12300 for two people depending on room category and departure time. The trip includes all meals and accommodation. For more information visit gadventures.com