We stood on a cliff at the southern tip of Deer Island, staring down at the rips, eddies, and whirlpools tearing through the water below. They ran clockwise, counter-clockwise, parallel to the shore, and perpendicular to it. There were places where the seawater actually boiled, like river rapids.
     We had heard that this was a great place to dive but I was beginning to have my doubts - diving in a washing machine during the spin cycle might be easier.
     But suddenly, as if someone had thrown a switch turning off some giant bath-tap, the rips and eddies began to fade, the whirlpools to slow, and within minutes the water had fallen almost perfectly still. The ebbing tide had run its course and slack water would be short and unpredictable. We geared up quickly and headed in.
     Under water, the shoreline cliff continued its path downwards in a steep, rocky wall. At first, there was little to indicate that we would actually see much here. This was Canada, after all, not the Caribbean, and visibility was less than 3m in the stirred-up water.
     But the wall suddenly exploded into colour and life. Red, pink and orange sea anemones appeared everywhere. Yellow sponges, some more than 1.5m across, spread out over the rocks. Bunches of stalked tunicates swayed in the water, while sea peaches clung together.
     Looking closer, we saw wolf-fish and lobster peering from crevices. Sculpin and sea raven shared ledges with fist-size hermit crabs, packed in among a mind-boggling array of starfish, sea urchins and molluscs. A school of pollack swarmed around us.
     The life and colour rivalled that of any coral reef I had ever seen. Yet it was different: if coral reefs are akin to a Monet painting, fragile and pretty, this was more comparable to van Gogh, a wild jumble of rugged brush-strokes.
     It was not much more than 10 minutes before slack water gave way to the first hints of the incoming tide: particulate matter suspended immobile in the water just a moment before was now in motion; tunicates swayed in the opposite direction; the arms of sea anemones began to vibrate as though in the wind.
     An underwater tornado seemed ready to hit us. We made a hasty exit back up to the beach and, before long, the water was once again a maelstrom of ever-widening rips, eddies and whirlpools. It would stay this way for another six hours. That's just how it is here in the Bay of Fundy, where the greatest tidal flows in the world roar in and out twice a day.
     The Bay of Fundy divides New Brunswick from Nova Scotia, and Deer Island lies close to Maine in the USA. In this section of the Bay of Fundy, known as Passamaquoddy Bay, the tide can rise and fall by as much as 6m.
     Along the mainland, where the shore has a more gradual slope than it does on Deer Island, the effect is incredible. Walk along the shoreline at high tide and the ocean will lap at your toes. Come back a few hours later and you won't even be able to see the water, let alone touch it.
     The only evidence that it ever splashed along the shore will be the vast tidal mudflats, dotted with boulders draped in blankets of seaweed, awaiting its return. It won't have long to wait.
     But it is these powerful tides, caused by the bay's funnel shape and the subsequent squeezing of water through the narrow confines of its 94-mile reach, that account for the profusion of life.
     The tides carry with them a steady stream of rich ocean nutrients, providing high-energy fuel to everything capable of surviving the chilly water temperatures.
     Sea life on the rocky walls isn't all that benefits: humpback, finback and right whales are all common here, as are dolphins and seals.
     There is a wildness here like few other places on the east coast of North America: stark cliffs of barren islands rise straight up from the sea floor; the smells of pine needles and salt water fill the air as coastal forests reach right up to the water's edge; bald eagles and ospreys control the skies.
     The best time to visit Deer Island is during the summer, when the days are warm and sea conditions more predictable. Few divers come here, and there are few facilities, though the owner of a charterboat called Sparky Too (www.angelfire.com/biz/sparkytoo) can provide equipment and directs divers to a small compressor operated from a private home on the island.
     And the US mainland is only a 20-minute ferry ride away - Four Seasons Sport and Scuba in downtown Calais provide gear rentals and air fills.
     Water temperatures range from 10°C in summer to zero in winter, so take your drysuit. With some 20 different sites around the island, this is an incredible place to spend time on or under the water, for those who have a healthy respect for the ocean's ebbs and flows, and are not thermally challenged.

Deer Island in the east


Northern red anemone


hermit crab


shorthorn sculpin


sea peaches


stalked tunicates


wolf-fish

A wave of apprehension washes over me as I watch the baggage-handlers load our massive amount of dive gear into the belly of the Grumman Goose.
     I look across the tarmac to my car parked outside the airport, and contemplate returning my five-day supply of socks and underwear to save weight. Then it occurs to me that I might need a change of underwear after this flight.
     Climbing into the cabin, it feels as if I am stepping back in time. This plane is older than me. The interior is a stark, well-worn, institutional grey. I squeeze into my seat at the back, against a stack of dive bags that wouldn't fit into the baggage compartments.
     The twin engines buzz loudly as the pilot brings the plane onto the runway, and we prepare to leave Port Hardy, at the northern tip of Vancouver Island. Ken, a diver from Alberta, turns around in his seat to face me. "I've heard about these flying boats," he says. "If you don't land 'em just right, they flip over."
     I didn't know that. Smiling, Ken turns around and relaxes into his seat.
     We begin the 20-minute flight north across Queen Charlotte Strait to our destination, Seymour Inlet.
     The seven of us will spend the next four days diving what the Guinness Book of World Records describes as: "The Strongest Current in the World. The flow of Nakwakto Rapids, Slingsby Channel, British Columbia, Canada may reach a rate of 16 knots."
     I begin to relax the death grip on my seat as I take in the view through the Grumman's scratched porthole-like windows. Beneath us, rugged uninhabited islands and islets are scattered about like rocks on blue velvet. Small pockets of ever-present fog hang lazily around the larger islands. Their vegetation, mostly scrub pine, is noticeably weathered from the fierce storms that punish this area.
     Even from half a mile up, I can see sinewy white streaks of current between the many islands in Slingsby Channel.
     The currents are always moving here. They stop only briefly every six hours, when the tide becomes slack.
     The plane banks to the left and in tiny Treadwell Bay we see Seymour Inlet Lodge, a collection of floating A-frame cabins a few minutes by boat from the dive sites of Slingsby Channel.
     As we begin to descend, I remember Ken's comments about the Grumman Goose. "Whoosh!" Water sprays up the side of the plane and over the windows as our pilot executes a perfect landing.
     Lodge-owner Bud Bowles and his son Chris greet us on the dock. Equipment junkies that we are, we immediately rip open our dive bags and start assembling our equipment with total concentration. The only interruption is the occasional crack-and-hiss as a tank is opened.

     Next morning we head out in the skiff to a Slingsby Channel dive site called Cliffhanger. It is raining lightly, and a misty fog has reduced visibility.
     "It's gonna get real ugly down there real quick, guys!" Chris begins the dive briefing. "If you see a patch of tubeworms bent over and doing this..." - here he bends his wrist with his fingers pointing downward and shakes his hand violently -"that's a downwelling. Don't go there. If you see a school of fish swimming down, but they're not moving, that's an upwelling. Don't go there."
     A lump is forming in my throat. I've never heard a dive briefing quite like this before. Should I be here? Peering overboard, I see twisting whirlpools and black, churning water. I quickly add up the many dives I have done here in British Columbia in an effort to relax myself. My dive buddy Miro and I look at each other, then at Chris.
     I can see my nervous reflection in his mirror sunglasses. With his shaved head, goatee and heavy fishing tackle hanging from his ears, he's nearly as scary as the water into which we're about to jump.
     "Welcome to Slingsby Channel," he says.
     The dive sites here are home to some of the strongest, wildest and most dangerous tidal currents in the world. All the water from the voluminous Seymour Inlet complex, which includes Seymour Inlet, Belize Inlet and Nugent Sound (some 1000 miles of coastline) flows through the narrow pass of Nakwakto Rapids four times a day. These currents bring with them massive amounts of oxygen and nutrients and support one of the richest underwater ecosystems in the world. It is this prolific and diverse marine life that we are here to see.
     Chris watches the water intently. Timing is everything up here. Enter too soon before, or too long after slack tide, and we will get blown off the reef and possibly end up in a very dangerous position.
     Finally, after several minutes of waiting, he gives us the OK. We have a two-minute window to descend and begin the dive. Two-by-two, we back-roll into the water.
     We descend, and are bucking a strong current. The steep, rocky reef below appears as an apparition as we drift down through the cold, dark water. As we descend deeper, shapes take on form.
     The sea becomes still - it is slack tide. Through the liquid night my dive light reveals a kaleidoscope of colours.
     The rock wall in front of me is covered with life. Large orange sponges, pink and purple soft coral and brilliantly hued anemones compete for prime aquatic real estate.

The marine life is packed incredibly dense here, an underwater Tokyo or New York. Giant barnacles, as large as fists, throw their cirri into the water column, searching for food. They pulse with an almost hypnotic effect. When they die, their shells become homes for a variety of small creatures, apartments of the deep.
     I scan empty barnacle shells, looking for any unusual tenants. In one I find a hairy cancer crab. It holds its black claws up at me in defence of its home.
     In another shell I find a grunt sculpin. This bizarre little fish resembles a large, cream-coloured tadpole with a long, pointed snout. Rather than try to fend me off like the crab, it attempts to hide further in its shell. It has little luck, as it is nearly as big as its home.
     While I pause to wait for Miro, I notice something peculiar about the rock in front of me. It has an eye! A perfectly camouflaged giant Pacific octopus, probably 60cm across, sits not more than 30cm from my mask. As soon as our eyes meet, it begins to move.
     It knows I see it. These shy creatures have a very high level of intelligence. Scientists believe the octopus is the most advanced of all invertebrates, capable of learning complex behaviours. Its dark mottled body becomes flushed red, and in one singular fluid motion it retreats into a crevice barely as wide as my finger.
     The current is starting to push me along. Light finning was enough to hold my position a few minutes ago, but I must now resort to more stealthy tactics.
     I find shelter behind a large rock while water rushes over the top. Like a soldier in a dug-out, I peer over the top in search of my next hiding spot, surveying the obstacles to safety. I make the dash, fin downward against an upwelling, and quickly get into position behind another large outcrop of rock.
     As I move forward, Miro moves to my last hideout. We signal OK to each other. Ahead I can see a vertical rock wall without a bottom, covered in tubeworms. They are bent downwards and shaking violently, and I move to the edge of the downwelling for a closer look.
     I know most of these currents are very localised, so there might be a chance of swimming across it. This one is huge, going at least 9m across the rock face. The tubeworms are bent straight down.
     As I turn to signal Miro to go back, I see something I have never seen before. My bubbles are going straight down!
     Panic comes over me as I realise I could have gone straight into the downwelling. We signal each other to turn back, then cautiously make our way up through a small kelp bed and wait on the surface for Chris to pick us up.

The wildness of Seymour Inlet and Slingsby Channel extends above water as well. There are several native archaeological sites, many as yet undiscovered. Grizzly and black bears can often be seen foraging along the shoreline.
     In the kelp beds outside the channel, resident grey whales are seen grazing for food. In summer, Pacific white-sided dolphins and killer whales patrol.
     Later that afternoon, safely back at the lodge, Chris is out bombing around in the skiff. His voice crackles across the marine radio at the lodge: "I've got some killer whales out here, get your cameras!"
     He barely slows the boat down as he approaches the dock, and doesn't tie up. We jump aboard and head out full-throttle until we see a pod of orcas running down a Pacific white-sided dolphin. They quickly lose interest in the dolphin and approach the boat.
     We are moving parallel to the shore, at about 10 knots. We count four whales, including two large males.
     Suddenly, the two large males surface, one either side of the skiff. I can almost reach out and touch one. "Wow!" is all any of us manages to say. Meanwhile, Chris is almost having a panic attack.
     "Holy s***!" he says. "Hold on, I think they're going to capsize us!"
     In all the years he has lived here, he has never seen killer whales approach so close. But after a few minutes they lose interest in us, and disappear beneath the surface. Miro and I shake our heads in disbelief at the spectacle we have just witnessed.
     "Wild place!" we say in unison, as Chris regains his composure and brings the boat across its wake to take us back to the lodge.
     Seymour Inlet Lodge, Canada's only floating dive centre, was destroyed in a fire last November. The good news is that the operation kept going from a refurbished tugboat, and the plan is to reopen much as before on May 15.
     Experienced coldwater divers considering diving in Slingsby Channel can contact the Lodge on 001 604 438 9421, or visit www.scubabc.com.

Queen Charlotte Strait in the west.


A fish-eating anemone in Slingsby Channel.


From the same area, the bizarre grunt sculpin



Diver in Slingsby Channel.


Still in British Columbia, a giant Pacific octopus


an orca


a brooding anemone


Gooseneck barnacles grow as big as fists in Slingsby Channel, providing housing estates for a wide variety of creatures