Transcript for the Piece Audio version of Ripple Rock meets its doom

AMB: Midship! (Midship.) Steer course 285.

Captain Larry Walter guides the Matanuska on a calm winter night. He?s taking the Alaska state ferry into a two-mile stretch of the nastiest water on the Inside Passage.

Seymour Narrows has some of the world?s fastest ocean currents. Like a thumb on the end of a garden hose, it squeezes the tides streaming between Vancouver Island and the North American mainland.

WALTER: Currents are tremendous in there, they can be up as much as 14 knots, and we?re restricted when we can go through there by the velocity of the current.

For comparison, a 3-knot current is enough to stop a sea kayaker. 14 knots? That?s about fast enough to stop a huge car ferry dead in its tracks. The Matanuska?s top speed is only 16 knots. But if the current reaches just 8 knots, the captain will wait for the tide to change, rather than fight it.

WALTER: Seymour Narrows is really the grand-daddy down here. This is really the maximum challenge along the B.C. coast.

As water speeds up, it starts to act crazy. Long chains of standing waves form. Water boils up like mushrooms. And whirlpools can appear without warning.

WALTER: I?ve seen nights with the ship, where we?ve gotten the ship into 1 of these whrlpools, and it?s turned the ship 90 deg in moments. It takes a lot of energy to turn this in an instant.

As difficult as the Narrows is today, it was far worse in the past. The British explorer George Vancouver called Seymour Narrows "one of the vilest stretches of water in the world."

Here?s how a documentary film from 1958 described the place.

FILM: Here at Seymour Narrows is a bottleneck. For here is a hidden mountain. For years, its twin peaks have been the greatest menace to navigation on the West Coast, Ripple Rock.

At low tide, the twin peaks sat just below the surface in the middle of the swirling channel. Ripple Rock claimed 120 vessels and killed at least 114 people until the Canadian government decided to fight back.

FILM: This is the story of how the killer rock finally met its doom.

The documentary was put out by Dupont-Canada. The chemical company provided the explosives to blow Ripple Rock to smithereens.

Canada?s Department of Public Works attacked the rock from below. They hired contractors to drill 500 feet beneath a nearby Island.

[DRILLING AMB]

The miners then tunneled half a mile horizontally beneath the ocean floor. Then, they drilled up into the twin peaks of Ripple Rock. Keeping the tunnels dry was a constant challenge.

[BOOTS SPLASHING, WATER RUSHING]

Miners went slowly, drilling small test shafts to make sure the tunnels didn?t flood catastrophically.

The 2-year project honeycombed Ripple Rock with shafts then filled them with explosives. Miners used a system of skate-wheel conveyors to deliver 70,000 cans of explosive, each can about the size of a fireplace log.

[SKATE WHEELS]

By 1958, Ripple Rock was stuffed with enough explosives to blow away 700 thousand tons of rock and sea water.

FILM: The whole operation was without precedent.

[POT UP jaunty music]

But it wasn?t just explosives manufacturers who got excited about the project. The CBC broadcast the destruction of Ripple Rock live across Canada.

CBC ANNOUNCER: There is exactly :35 to go. [BEEPING] I don?t know about you, Ted, but I?m really tense right now. ?

The blast was timed to a low tide to reduce the effect of any tidal wave.

Police evacuated everyone within a 3-mile radius. And insurance companies told homeowners to take everything off their walls before the blast.

[COUNTDOWN FINISHES. EXPLOSION. WHOOSH.]

You can hear rocks falling on the bunker a half mile from the blast site.

After the smoke cleared, officials said there had been little effect beyond the immediate blast zone. But how about Ripple Rock itself?

Nearly 50 years later, the Matanuska makes its way through Seymour Narrows. As 3rd Mate Shannon Meyer explains, the conditions are gentle tonight, with a 4-knot current helping the ship along.

MEYER: Next week, Seymour gets a 13-knot ebb, so 4 is nothing, relatively speaking.

The currents of Seymour Narrows are still a force of nature that mariners ignore at their peril. But Ripple Rock is only a faint echo on the depth finder of the menace it once was.

FILM: Now ships can sail right down the middle of Seymour Narrows, for Ripple Rock, the immovable object, has been conquered, conquered by an irresistible force.

[MUSIC CRESCENDOS]

On board the Matanuska, I?m John Ryan.

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