Killer whales are somewhere out there. And all I've got is this kayak

Paddles at the ready, Marcus Waring enters the amazing stretch of water that separates Canada's mainland from Vancouver Island

Touring our remote kayak camp, the group inspects the two outdoor loos among the pine trees. Nature's Throne is a pit toilet complete with seat. The Rocketship Toilet has a burner which is switched on late at night - we flinch, fearing an accidental Brazilian-by-fire. And, curiously, an airhorn next to each loo. For if you run out of paper?

Touring our remote kayak camp, the group inspects the two outdoor loos among the pine trees. Nature's Throne is a pit toilet complete with seat. The Rocketship Toilet has a burner which is switched on late at night - we flinch, fearing an accidental Brazilian-by-fire. And, curiously, an airhorn next to each loo. For if you run out of paper?

"It's in case a black bear or cougar appears," Chris, Luke and Leif, our guides, explain. "Only use it in an emergency, as it will scare the hell out of us and we will come running." My sympathies would be with the person caught with their pants down by wild beasts.

Frontier Travel offers a four-day tour kayaking with killer whales in the vast sea channel of Johnstone Strait between Vancouver Island and the mainland of British Columbia. Part of the Inside Passage up to Alaska, here killer whale pods hunt salmon in the deep, cold waters below pine-covered mountains.

Overnighting at the Fairmont Hotel, Vancouver, an internal flight north to Campbell River and a ferry crossing lands you on Quadra Island, a mellow, wooded place. At Taku Resort, chalets in the shade of tall pines look east across Rebecca Spit to the snowcapped Coast Mountains inland.

Our group meets at the headquarters nearby where John, one of the owners, explains the tour. There are two families from Michigan: Brian and Amy Brege with teenagers Casey and Adam, and Doug and Ann Rau with Stephanie and Brent. Derek and Susan are from near Seattle and are in their late twenties.

"In the south of Vancouver Island there are 79 orcas and 80 tour boats pursuing them," John says. "But where you are going is different." Many things are unknown about this enigmatic species of dolphin, especially when they all but vanish in winter. Historically, the second most widely distributed mammal after humans has been misjudged. Orcinus orca was believed by seafarers to be a ferocious killer. As late as the 1970s US Navy diving manuals noted that these ferocious creatures would "attack human beings at every opportunity".

The highest concentration of orcas in the world lives around the Robson Bight (Michael Bigg) Ecological Reserve. This area is where the Northern Resident whales uniquely rub themselves underwater on the steep beaches, using them as a giant loofah. Explanations for this behaviour vary; the current theory is that they just do it for fun.

Speeding for three hours to the camp in an aluminium catamaran the following morning, we encounter the treacherous Seymour Narrows which have the highest tides in the world and where 114 mariners' have been recorded drowned.

At the beach on West Cracroft Island where the kayaks are kept near the camp, the departing group welcomes us by trumpeting on bull-kelp, a tubular seaweed. They appear to have gone a bit Lord of the Flies. But those stranded schoolboys did not have a bucket shower made of driftwood with optional hot water and superb views, along with comfortable dome tents on a rocky headland.

The guides produce an impressive selection of meals from the driftwood kitchen. Breakfast can be granola mixed with yoghurt and juicy blueberries, followed by French toast, or bear-shaped pancakes covered in maple syrup. Sockeye salmon is a lusty red. John's words on Quadra now make sense - the tours are nicknamed "float and bloat".

Luckily there is kayaking to work it off. At the beach the group carries long double and single craft to the water. The first foray involves getting to grips with my Current Designs sea kayak. Paddling in a stiff headwind gets the muscles working as the sun beats down and we head through Boat Bay and out to the second of the tiny Sophia islands.

Frustratingly, the orcas keep appearing when we are on dry land. Several tall fins pass by, rising and falling rhythmically. The guides listen on their radios to Eagle Eye, a clifftop research station, to hear where they are. The sighting rate is more than 90 per cent and guests have had them swimming under the kayaks before, although very occasionally groups don't see them at all. Tourist brochures are not written in whale-speak.

Another day-long paddle takes us to a beach and a hike through old woods up to Eagle Eye, where researchers with telescopes are studying the whales below, tracking their movements and identifying them by scars on their fins. "Maybe this second bull is B8", says one, while another volunteer taps at a laptop.

Sunsets in the camp means drinks on the rocks, watching the odd cruise ship returning from Alaska or floatplane bumble past. Watches have been removed and time has reverted to paddling, calls of nature and the dinner gong.

On the first evening we get a floorshow. A full moon rises over the dark outline of the mountains opposite. I make the flippant comment that we need some dorsal fins to pass across the reflection of the moon on the water. Ten minutes later, dark shapes slip close by the rocks, exhaling noisily like snorkellers and, for the killer blow, a mother and her young calf surface together in the moonlight for one of those defining moments captured in memory alone.

On another occasion, listening to them talking underwater, their conversation picked up and relayed by a microphone and speaker, had also been surreal. Their haunting exchanges at sunset, when they passed beneath the pink mountains, sounded both familiar and alien as they called to each other in the darkening waters.

On the last morning we head out early. On a nearby beach a black bear is searching for molluscs near the water. Out in the Strait, low clouds silently blanket the mountains while the water gently rises and falls as though breathing steadily in a deep aquatic sleep.

While the others examine purple starfish, I paddle into the middle, willing the whales to appear. It feels like glimpsing infinity out here, where you could disappear into the scenery and just keep going. The giggling group has been eating a sea urchin that Leif cracked open. "It tasted like old tuna," Amy says. Brian is even less enamoured. "It had the consistency of snot," he says.

Catching the ride back to Quadra Island, we greet the full moon with howls of laughter at Brian's tale of how he was on Nature's Throne that morning when some local wildlife ran straight past his feet. "Squirrel!" Brian yells. "Man, I nearly went for that airhorn." The guides would have found it funny, eventually.

GIVE ME THE FACTS

How to get there

Air Canada (0871 220 1111; www.aircanada.ca) flies to Vancouver from Heathrow from £515 return. Pacific Coastal (001 604 273 8666; www.pacific-coastal.com) flies on to Campbell River from CA$166 (£73).

Where to stay

The writer was a guest of the Fairmont Hotel Vancouver (001 604 684 3131; www.fairmont.com), 900 West Georgia Street, Vancouver. Room only costs from CA$326 (£143) per night. A self-catering apartment at the Taku Resort (001 250 285 3031; www.takuresort.com) on Quadra Island costs from CA$112 (£50) per room per night. Frontier Travel (020-8776 8709; www.frontiercanada.co.uk) has a four-day Johnstone Strait Tour, July toSeptember, from £449, based on two sharing, with guides, meals, kayaks, tents and boat transfers.

Further information

Canadian Tourist Board (0906-871 5000/calls cost 60p per minute; www.travelcanada.ca)