Bellis could see the page the grindylow had opened. She had seen it before, in her room, and in Croom Park, months before. Rough scribbles suggesting engines, red lines of force and striae of rock types crosshatched in ink. The hidden positions of The Gengris on the Cold Claw side; the paradoses and defenses; the traps.

Understanding was uncoiling in Bellis like cold water. She remembered the conversations she had had with Fennec, when they had first grown close. She remembered his stories, the extraordinary tales of his travels. She remembered what he had said.

If you can get across the Cold Claws, if you can reach the islands and the far shores, if you can trek across those miles and miles of punitive geography, to the Shatterjack Mines and Hinter, to those hungry trade partners and those untouched miles of resources, then you are made. But most can’t make it, because the route is so terrible; because you can’t come at it from the south, because The Gengris are in charge of the southern tip of the Cold Claw Sea and won’t let outsiders pass.

But what if youcould reach it from the south, directly, Bellis thought, coming straight? Not into some tumbling fucked-up overland caravan shedding its goods and machines and crews like spoor across the mountains and the grasslands, but by ship. What if you could sail from New Crobuzon, safely past The Gengris in safety, and straight up to the north?

"My good gods," she murmured, and stared at Fennec. "A canal. They’re planning a canal."

It made such sense. The rock ridge between the freshwater of the Cold Claw Sea and the Swollen Ocean’s brine was only thirty, forty miles wide in places, its ridges wrinkled with valleys. Bellis could picture the work. A prodigious project, true, but what a prize.

Ships sail north from Iron Bay, skirting the harsh coastline of Lubbock Scrub and the Bezheks, then out to sea to avoid the ruins and residuum of Torque by Suroch, skirting the straits between the Pirate Islands and the mainland; and then a week’s sailing north of New Crobuzon, the flint spines that shield the Cold Claw Sea would rise to port, to the west.

But no longer impenetrable. Breached.

A wide runnel scored at the bottom of a strath. Tall ships and steamers passing sedately between overhangs and scree landscapes.

And there would be locks. Huge locks segmenting the canal, raising the brackish water in stages, massive wooden doors and careful engineering, bringing the ships closer to the Cold Claws, step by ponderous step. They would ascend the strata of the canal while the ocean barnacles clinging to their hull grew weak and died as the water lost its salt.

Until-what?

Out.

The rock monoliths part before the ships, and the canal bleeds into the deep waters of the freshwater sea: the Cold Claw Sea.