A few years later, in 1746, the Spanish gave up and started sailing their treasure ships round Cape Horn instead. Panama was neglected, though not allowed to trade freely with the rest of Europe. In 1821 the Panamanians declared themselves independent… and joined Bolivar's Greater Columbia.

Which neglected them. There were revolutions.

Before the Spanish came to Panama there were over sixty native tribes living in the area. Afterwards, three.

Then somebody found more gold. Far to the north this time, in California. The plains of North America, still under invasion, were far more dangerous than a sea trip from New York or New Orleans to the Río Chagres, a short paddle and a quick mule ride to the Pacific and another voyage from there to San Francisco: Panama was back in business. The short paddle and quick mule ride was so much fun the forty-niners called it the Road to Hell. They died in droves, mostly from disease.

Some already rich Americans formed the Panama Railroad Company. Somehow persuaded of their righteousness, the Columbian government granted them a monopoly.

It made money.

The track ran from Colón to Panamá, over one of the old Spanish gold trails. Then a golden spike was driven into its heart, thousands of miles to the north-west, in the United States of America: the first rail route from sea to shining sea was in operation.

So people began to neglect Panama again.

Ferdinand, Vicomte de Lesseps, builder of the fabulous sealevel, distance-reducing, desert-crossing, Empire-linking, all-singing, all-operatic Suez Canal, a cousin of the French Empress, winner of the Grand Cross of the Legion of Honour, recipient of an English Knighthood, member of the Academy, began work on his world-stunning scheme to build a sea-level canal through the isthmus of Panama in 1881.

Gauguin worked on it, artist among the artisans.

Twenty-two thousand people died on it.

And in 1893 it was over; the company — La Compagnie Universelle du Canal Interoceanique, shunned by governments and banks, worshipped by the small investor, disseminator of bribes to press and politicians — crashed, and five directors were condemned. Eiffel, constructor of the soaring Tower, was laid low. De Lesseps was sentenced to five years in prison.

He died next year, heart excavated.

The United States of America was the major regional power now. It was determined to have a canal. First choice became the route through Nicaragua, but the manager of what remained of the French company sent all members of Congress a Nicaraguan postage stamp showing a volcanic eruption. He also made the point that Panama was outside the volcano belt; it didn't have earthquakes. Was there not an arch still standing (the famous Arco Chato, or Flat Arch, part of the church of San Domingo) which had stood intact for three centuries, in Panama City?

Congress was convinced. The word went out that it would be a good idea if Columbia let La Compagnie Universelle sell all its rights to the US. The Columbian Congress disagreed, and wouldn't ratify, no matter what President Roosevelt wanted. Incredibly, an uprising in Panama City played right into the US's hands, and when Columbian troops were sent to squash it, Congress sent a gunboat. Washington recognised the independent republic almost before it was proclaimed. It was 1903.

The new government of independent Panama thought it was a neat idea to cede partial sovereignty over a strip eight kilometres wide on either side of the canal route to the United States 'in perpetuity' for ten million dollars down and a quarter million a year (the latter eventually raised to close on two mill, when it got embarrassing).

The diseases were vanquished, despite everything. The problems of geography and topography were conquered by brains, brawn and lashings of cash. The temporary rail system built to help construct the canal was the greatest railway network in the world at the time. Mountains were moved, rivers dammed, forests drowned, islands created. The Zone became an island of clipped lawns in an ocean of jungle.

In August 1914, while the Great War in Europe was still beginning, the first ship passed through the new canal.

In 1921 the US paid $25 million to Columbia, to compensate for the loss of the isthmus called Panama. Cut to:

1978:Jimmy Carter agreed a new treaty. In 2000, it would all be given back to the locals.

(The Panamanians never had liked that 'in perpetuity' clause.) The Zone became the Area, but most people still called it the Zone. Pineapple Face spoiled things a little, but not so you'd notice. Things went on. The second millennium crept closer. And that was as far as Hisako's guidebooks took her.

The rain was warm and the air smelled of the land's own heat; vegetable and intense, like something that had willed itself into being through a chemical spell, without the intercession of the sun. Six o'clock and it was already dark, and the rain fell steadily, glowing in the lights of the Nakodo, swinging about her mooring in the gentlest of evening breezes. The waters of the lake looked dull and flat and oily, covered with the ever-changing patterns of the big raindrops, ephemeral dots and dashes on the slowly moving surface. The air was so thick and humid it was hard to believe the rain could fall through it so fast.

'Ms Onoda! Hisako! You'll get soaked!

She turned from the rail to see Mandamus waddle up, coming from his cabin on the main deck level. Hisako brushed a few droplets from her fringe of dark hair; the rain was falling almost straight down, and the deck above had sheltered her. But Mandamus liked to fuss.

Mr Mandamus, the Alexandrian, portly and effusive, with greyly olive skin and dyedly grey hair, a friend of mankind, peripatetic expert in multitudinous fields and reputedly holder of degrees from universities on three continents, took Hisako Onoda 's hand in his and kissed it precisely: Hisako smiled as she always did, bowing a little.

Mr Mandamus offered his arm and she took it. They walked along the deck, heading forward.

'And where have you been today? I was a little late for lunch, but you ate in your cabin, I believe.

'I was playing, she told him. The deck was dry near the superstructure, spattered with dark drops near the rails.

'Ah, practising.

Hisako studied the deck, wondering who'd decided the pattern of tiny diamond shapes on the metal was the best one for providing grip. 'I worry about becoming out of touch; rusty.

'Rust is best left to the vessels, Ms Onoda, Mandamus told her, gesturing. They arrived at the forward limit of the Nakodo's superstructure, looking out over the rain-battered hatches — bright under the masthead lights — to the forecastle. To starboard, the lights of Le Cercle and the Nadia burned through the night and the warm rain, floating islands of light. in the darkness. She wondered what Philippe was doing. When they'd made love the evening before, after the swim through the ruins, before the nightmare, Philippe had held her shoulders, his arms through her armpits, clutching at her shoulders from underneath, arching her. She'd had the dizzying sensation of still wearing the scuba gear, the straps pressing into her skin. She'd remembered the silky warmth of the water, and the sight of his long, tanned body sliding through it, wave lights rippling from the surface like grid lines across the sweet geography of his back and legs.

'… Hisako? Are you all right?

'Oh! She laughed, and let go of Mandamus's arm, which she'd been gripping too hard. She clasped her hands at the small of her back and walked quickly on, desperately trying to recall what Mandamus's last words had been. 'I'm sorry, she said. I am acting like a schoolgirl, she told herself. Mr Mandamus caught her up, offering his arm again as they walked, so that it stuck out between them like a podgy guardrail. It had been something about rain and mud (how romantic!). 'Yes, yes it's terrible. But they are fixing this, no?