When dealing with the Pacific Ocean, it doesn’t take much to get spanked. A Vancouver Island kayaker was surfing the massive wave pile known as Okisollo Upper one minute and was a distant swimming speck in the ocean the next. A hundred-horsepower saviour hit the throttle and took off after the helpless buoy as the 10-knot tidal current carried him into the blue expanse.
With tidal rapids like Okisollo and Skookumchuck being on the itinerary of today’s best paddlers and photographers, the rapids are rolling easily off the tongues of increasing numbers of paddlers, but landlubbing first-timers testing the tidal waters quickly realize that when it comes to the ocean, the ball looks the same but the field is something altogether different.
Tidal rapids are the result of a rhythmic interaction between the moon, continents and ocean water. The moon’s gravitational force pulls the ocean along behind it—picture some groupies chasing a rock star. continents act like bouncers, blocking the ocean’s crush, forcing the swell to crowd against the land as high tide.
So, as the tide goes from low to high and the Pacific Ocean rises against the shores of British columbia, ocean water pushes against Vancouver Island and pours in behind. But, in the constricted northern section of the Inside Passage, the tide is impeded by islands. As more and more water pushes against the islands it rushes around them, like it would around rocks in a river.
With salt water being denser than fresh, tidal exchanges being as high as four metres and volumes reaching thousands of cubic metres per second, tidal rapids can make rivers seem like a sidestreet gutter after a light drizzle.
Just like at better-known Skookumchuck, a rock shelf just below the ocean’s surface creates an ever-changing whitewater factory at Okisollo. The speed, size and nature of the wave changes as the tide rises and the current strengthens. Upper Okisollo morphs from manageable play wave, to breaking wave, to Zambezi-sized frothing hole, to glassy smooth in a couple of hours. As high tide passes the waters equalize on both sides of the shelf and the whole process is reversed.
“Tidal rapids are as dependable as the moon,” says Zak cross, a Vancouver Island kayaker. “Even when there’s no water in the rivers the tidal rapids are flowing.” cross has been playing in tidal rapids since 1996, sometimes using a motorboat to explore the near-infinite and rarely visited tidal rapids hidden in the maze of islands and channels around Vancouver Island.
A few minutes later the motorboat reaches the swimmer and helps him into the boat, no doubt grateful—and newly appreciative of what the moon has to offer whitewater paddling.
This article first appeared in the Summer 2006 issue of Rapid Magazine. For more great content, subscribe to Rapid’s print and digital editions here.
