We're going on a bear hunt ...

Some of Manitoba's wildlife comes with fearsome claws attached – but there are gentler creatures too, as Mike Unwin finds out in the Arctic Ocean

Is this the real life?" I warble through clenched teeth into my rubber mouthpiece. "Is this just fantasy?" There's no accounting for what tunes enter your head when you're being dragged backwards through the Arctic Ocean, and instructed to sing "as loud and high as you can". Happily, this is no water torture. I am here as a guest of Seal River Heritage Lodge on Canada's Hudson Bay. The idea is to get closer to belugas, the small white whales that gather here in their thousands every summer. I have already seen them from the air: scattered like rice over the wrinkled tablecloth of the bay. But now, face down in the dark, choppy waters, meeting one is a more daunting prospect.

A dry suit keeps me both warm and buoyant. Andy MacPherson, our guide, is some 20m behind me in the boat, paying out the line in which my feet are looped. I should know what to expect – we've had a thorough briefing; even watched a DVD – but I can feel my confidence ebbing away, along with my warbling, into the murk.

Then I hear it: an electrical hissing and buzzing, interspersed with bright, R2-D2-style clicks and whistles. Not for nothing are belugas known as sea canaries. On cue, a pale shape emerges at the sepia edge of my vision. As I'm trying to make sense of this apparition, another whale arrives – much closer. Smooth, muscular and Dulux white, it passes just two metres below me and stares up with naked curiosity. I can see its bulging forehead and endearing dolphin smile. Then another looms up and scrutinises me, eyeball to eyeball, a foot in front of my face.

For the next 15 minutes I hang there, hardly breathing, as the belugas encircle me - almost, but not quite, making contact. Their chatter pulses in and out of the murk like the tuning of a long-wave radio. "Who's the clown on the rope? Doesn't he know any Lady Gaga?"

Spectacular as the belugas are, it is another large, white Arctic mammal for which this area is best known. Before we land at Seal River Lodge, I spy two things below: a cluster of wooden buildings that must be the lodge; and something large and white ambling past them.

Tundra swans flap heavily away as our Turbo Beaver floatplane touches down and taxis to the landing jetty. Andy and fellow guide Terry Elliot ask us to stay on the boardwalk as we wait for the luggage: "Don't want you guys meeting any bears just yet." The message is repeated as hosts Mike and Jeanne Reimer welcome us into the lodge. "That front door you just came through?" says Mike. "Well, it's no longer a door. You never go out of it – unless you're with one of us."

Nobody protests; this summer's attack on a group of young British explorers in Svalbard, in which a student was killed by a polar bear, made headlines on both sides of the Atlantic. As we slap on bug spray and don boots for our first hike, our guides run through the bear safety drill. Terry reassures the more anxious among us by revealing his arsenal of firecrackers, pepper spray and shotgun. He stresses, though, that this gear is to be used only as a last resort, and that a lusty yell and well-aimed stone will usually do the trick.

Soon we are tramping along the shoreline below the lodge. The retreating tide has exposed a moonscape of glacial boulders across the mudflats, and it is behind one of these we meet our first bear – having a kip. The long neck swings up, roman nose testing the breeze, before the head settles on massive forepaws, black eyes fixed on our approach.

With a relaxed individual like this one, Andy explains, we can get within 50 metres. So that is exactly what we do – single file at first, so as not to "intimidate" him; then, having reached a strategic shingle ridge, spreading out slowly to allow everyone a decent view. On the face of it, you couldn't meet a more harmless-looking creature. The great, furry mound is outlandishly white against the tundra backdrop, and rolls over as though for a cuddle. But nobody's going any closer. It's a thrilling moment: wall-to-wall wilderness, with just us and – a few paces away – the world's largest terrestrial predator. After a while, the bear gets up, shakes himself like an over-sized Labrador and saunters up the beach.

During the next few days we become more accustomed to the bears and venture a little further into their world. It's a wild place, certainly, but it's far from barren: fireweed and marsh ragwort splash their colours across the shoreline; dwarf willows peep from the stream edges; and crowberries and cloudberries carpet the tundra's springy mattress.

Birds are everywhere. Sandpipers, godwits and yellowlegs keep up a shrill piping as they commute between tidal pools, while sandhill cranes and Canada geese cross the tundra in bugling skeins. Twice, a gyr falcon sweeps like a fighter jet through the panicked ranks of ducks and shorebirds.

Even when out of sight, however, bears are seldom out of mind. While we crouch to photograph a mountain avens or train binoculars on a red-throated loon, Terry and Andy keep up their methodical scanning of distant ridges and nearby bushes. Should we forget, the huge, five-clawed tracks printed across every beach provide an eloquent reminder.

Truth be told, there is no better viewing of bears than from the lodge. Inside the wooden observation tower, we can watch them roam the landscape at our leisure. Mealtimes, meanwhile, are frequently interrupted by one swinging past the windows; our waiters shrug resignedly as we kick back chairs and scramble for cameras.

On such occasions, it is us who feel like the captive exhibits. But the lodge makes a delightful zoo. Inside, safe from inquisitive bears, wild weather and ravenous mosquitoes, we enjoy fabulous food - caribou wellington, blueberry muffins, snow goose casserole with wild rice - all prepared from treasured family recipes using tundra ingredients. And after stuffing our faces, we sink into armchairs by the wood stove to enjoy the view outside: the constant play of light and tide; the slow-burn slideshow of clouds, sunsets and rainbows.

This summer window is a brief one. Even now, the season hints at change: on our final hike, we spot snow geese overhead and caribou prints underfoot, outriders of the great migrations that will soon be passing this way.

On our last morning we cross the bay to Hubbard's Point, a remote spit some 15 miles north of the lodge. Belugas surface in the channel beyond, and a single bear lopes away from our approach. Further inland, a loose stone circle is more than arbitrary geology: this is a tent ring - the stones arranged where they once anchored the walls of an Inuit tent. Who knows how long they've been here. It's a reminder that this harsh land was once a home for people, too. People made of sterner stuff than me.