British Columbia's islands are summits: the mountain range continues below the water

Look at a map of Canada's Pacific coast and you see something that reads like a printing fault: a strip of land frayed into hundreds of vertical shreds, with the sea pushing between them in long narrow cuts. It looks as though something violent happened there.

Something did, though slowly. What that map shows is a partly submerged mountain range, and the islands are the part still above water.

01 Sixteen hundred kilometres against the Pacific

The Coast Mountains run some 1,600 kilometres north to south and average 300 in width. Their highest point lying entirely inside the province is Mount Waddington, at 4,019 metres, northeast of the head of a fjord. Hold on to that detail: a four-thousand-metre summit round the corner from an arm of the sea.

That range does not end cleanly at the coast, as ranges do almost everywhere else. It goes into the ocean and keeps going. What a map shows as shoreline is really the shifting line where water happens to cover the mountain, and that line cuts the slope halfway up.

The numerical result is a coastline of more than 27,000 kilometres for a province that, measured straight north to south, is little more than a thousand across. That ratio of twenty-five to one is the exact measure of how tangled the edge is.

02 What the ice did

The agent that carved all this was ice, and the province still keeps the machinery: the Coast Mountains hold the largest temperate-latitude ice fields in the world. During the glaciations, enormous tongues of ice came down the existing river valleys and dug them far deeper than any river can.

The difference is geometric and visible at a glance. A river cuts a V-shaped valley, narrow at the bottom. A glacier, which fills the whole width of the valley and drags rock along the floor and the sides, leaves a U: near-vertical walls and a flat, very deep floor.

When the ice withdrew and sea level rose, the ocean came in along those U-shaped valleys. A fjord is nothing more than that: a flooded glacial valley. That is why the walls drop sheer, and why, sailing up the middle, you see no beach on either side.

03 Six thousand islands that were once ridges

The same ice scoured channels in every direction, following pre-existing fractures and valleys. Geography texts put it bluntly: the ice-scoured channels are so numerous and varied in direction that the rocky coast is divided into thousands of island blocks, some large and mountainous, others merely rocky points or reefs.

Out of that come the province's roughly 6,000 islands, nearly all uninhabited. And out of it comes a feature you notice the moment you look at them: they are aligned. They are not scattered at random, as in a volcanic archipelago; almost all of them run in the same direction, because they are the strips left between one channel and the next.

Put as simply as possible: if sea level dropped two hundred metres tomorrow, those islands would stop being islands and would look like what they are, the high parts of a continuous landscape.

04 Why a fjord is deeper inside than at its mouth

There is a detail about fjords that surprises anyone arriving by boat and watching the depth sounder. Almost all of them are deeper inside than at their own entrance. That is the exact opposite of what a river does, deepening as it approaches the sea.

The reason is that the glacier lost power as it neared its end. It excavated at full strength along the upper and middle stretch, and at the mouth, where it melted, it stopped excavating and dropped the material it had been carrying. What remains there is a sill of rock and moraine, a submerged step acting as a stop.

That sill has biological consequences: it limits water exchange with the open ocean and makes the bottom of some fjords behave like an isolated basin. It is one of the reasons these waters concentrate so much life, and why salmon, whales and seals behave here as they do in few other places.

05 A province where the sea is the road

All of the above has an everyday translation. Building roads across relief like this is enormously expensive, and along many stretches simply impossible: there is no coastal plain to run along, only slope falling into water. Some 75% of the province sits above a thousand metres and only 5% is arable.

The solution was to stop fighting the geography. The ferry network works as an extension of the road network: the boats carry cars, run to scheduled timetables and connect stretches of asphalt separated by water. There are whole communities reachable only by boat or light aircraft, and they are not exotic exceptions: they are part of the system.

A counterweight is worth adding. In the southwest corner, where the relief leaves some room, live most of the province's 5.6 million inhabitants. The rest of the territory is enormous and practically empty, with 12.5% of the surface — around 114,000 square kilometres — under some form of protection.

06 What this changes for the traveller

The first consequence is that here the itinerary is dictated by the boat timetable, not the map. Two points thirty kilometres apart in a straight line can demand a three-hundred-kilometre detour by road or a crossing with countable departures. Before booking accommodation, check the schedule, not the distance.

The second is that the journey is part of the trip and not a formality. Crossing an arm of sea between mountain walls, with the forest dropping to the water, is exactly the landscape you came for. Counting it as time lost is an accounting error.

The third is about scale. A province of 944,735 square kilometres is not toured: you pick a piece. The southwestern peninsula and the big island are one trip; the northern fjords are another; the dry interior, on the far side of the range, is a third that does not even resemble the others. Attempting all three is the most efficient way to see none of them.