It took a few moments to register what I was looking at: an island in a lake inside another island in a river in a forest. A Russian-doll landscape to make you contemplate the nature of infinity. Then there was another river - black this time instead of muddy brown - so wide that the Boeing 747 did a 180-degree turn entirely within its banks. After this, the sight of a modern city rearing out of the jungle was both reassuring and baffling.
But despite its dramatic setting on the banks of the 8km-wide Rio Negro, Manaus is not normally considered a tourist destination. A confusion of high-rise blocks, stilt-house shanty-towns and streets of roller-shuttered shops, it is usually just an overnight stop (or not even that) on the way to the tranquility of a jungle lodge. Two million people and streets full of traffic don't exactly sit easily with our rainforest fantasies. But spend a couple of days here and you'll see a reality that is stranger than illusion.
The key to the city's history is the multicoloured dome that you keep glimpsing between the concrete towers, the immense neo-classical Manaus opera house, a relic of the time when this was one of the richest cities on earth: electricity before London, telephones before Rio, electric trams while New Yorkers were still pulled by horses.
This wealth came from a world monopoly in wild rubber. Migrant workers thirsting for "black gold" poured into the Amazon and became stranded here when the boom turned to bust. How it all went wrong is a tale of skulduggery and subterfuge - or not, according to whom you believe. "Your Henry Wickham destroyed the Amazon," said riverboat skipper Josimar Bezerra, referring to the Englishman who in 1876 smuggled 70,000 seeds of Hevea brasiliensis to Kew Gardens. These ultimately gave rise to the plantation-grown rubber from Ceylon and Malaya, which sent prices plummeting.
But in 1876, Dunlop's pneumatic tyre was a decade away and Henry Ford was 13 years old. The crash took nearly 40 years to come. Nowadays, adding insult to injury, if the descendent of a rubber-tapper buys a condom from a farmácia, the print on the pack tells him it's imported from Malaysia.
But something keeps the city going. Down in the Centro, there are shops selling televisions, stereos and the latest computers. To prevent the Amazon becoming depopulated, the Brazilian government made Manaus into a free-trade zone. Multinational electronics companies set up factories in the Distrito Industrial, and visitors from the rest of the country can be seen checking in at the airport with trolley-loads of tax-free goods.
Despite being 1,600km from the sea, Manaus even has a beach, which appears above the water between August and December. Every Sunday, fleets of buses converge on Ponta Negra for beer, football and music. Crowds throng a row of open-air bars pumping out competing music at maximum volume as sweaty, near-naked dancers gyrate on makeshift stages. Couples in the crowd give displays of energetic forró - a bit like a sexy ballroom on fast-forward. And like a folk-memory, the place remains a magnet all year round, even when the white sand is under the 10m annual flood and the exclusive preserve of the fish.
Also unchanging, for now, is the ritual that takes place every morning at a wrought-iron and glass structure near the floating port. Built when Manaus was still the Paris of the Amazon, this art-nouveau fish market was modelled on the Parisian Les Halles.
On slabs down the sides of its long hallway are the inhabitants of the region's rivers and lakes, en route to the city's kitchens. Armour-plated cascudo catfish (eat with care as the fragments of carapace are like broken glass). The perch-like tucunaré, with an eye-spot on its tail - a favourite on restaurant signboards. The shark-like piraíba, mother of all catfish and alleged swallower of unwary swimmers. The nut-crunching tambaqui, the connoisseur's favourite. In all, as much biodiversity as you'll see at most jungle lodges.
What you won't see, however, are the man-sized fillets, like outsize kippers, that used to be laid out here until a couple of years ago. Following a huge fall in numbers, the Brazilian government has at last banned trade in pirarucu, the world's largest freshwater fish. Once abundant but now embattled, these giant Technicolor fish - 2m long and weighing 100kg - are a fitting symbol of the Amazon. Most visitors and Manauenses never see one - they have retreated into myth. But you can see them face to face just a half-hour taxi ride away in the Japanese aquarium - an unlikely setting for one of the wonders of the natural world.
The other piscine legend not found on the fishmonger's slab is the piranha. This is not for reasons of scarcity - far from it. Rather, it is not considered to be of any culinary value (although piranha soup is supposed to be an aphrodisiac). For your close encounter with this species, now is the time for a few days at a jungle lodge.
Just half a day's travel from the bustle of Manaus is the deep lacustrine calm of Amazon Lodge. As the wooden fishing boat pulled away from the riverside and the city receded into the distance, we seemed to sink into another time. Other boats, crowded with colourful hammocks, criss-crossed the "River Sea" bound for tributary towns several days away - the spirit of the Portuguese seafarers living on five centuries after they arrived on this continent.
Down here, the confluence is no longer a simple T-junction but a confusing horizon of overlapping grey strips. But the commandante navigates us safely to the small township of Careiro, where we transfer to an all-terrain vehicle for a rutted stretch of track. Then it's on to water again: by launch via the Rio Mamori and into the forest's deep tissue.
In traditional style, the lodge floats on great trunks of balsa-like assacú, which rise and fall as the lake swells and contracts. After lunch, our guide takes us for the promised encounter with the piranhas. Tackle is as basic as can be: just a few feet of line and a long-shanked hook, baited with a sliver of fish. But there is no boiling frenzy. At first this disappoints, but when the first red-bellied piranha is swung in, its mechanical dentition brings gasps. Although normally no danger to swimmers, the potential of their cookie-cutter teeth to inflict carnage is beyond doubt.
At night, we encounter what some operators bill as "flashing alligators". From the safety of a big canoe, we sweep a torch around the backwater margins and marvel at the red eyes in what we took to be empty water. If your guide can find a pair of eyes not too far apart, he may even grab one of the dazzled cayman (up to a metre long) by the scruff of the neck, for a hands-on natural history lesson - original inhabitant and interloper in a moment of awkward interaction.
After two more days of swimming in the lake, forest walks and exploring this water-world by fishing canoe, we contemplate our stay through the lens of a caipirinha - a piece of regional alchemy whereby stomach-burning cane rum is transformed into a deliciously smooth cocktail by the addition of sugar, limes and crushed ice.
And inevitably we find ourselves wondering: which is the real Amazon? This, or the city? The answer, of course, is that they both are.
· Jeremy Wade is presenter of Jungle Hooks. The documentary series will be broadcast in its entirety on Discovery Home & Leisure on December 20.
Way to go
Getting there:
Varig Brazilian Airlines (020-8321 7170, varig.co.uk) flies Heathrow-Manaus via São Paulo from £796 return. Or fly to São Paulo from £656 return and use a 21-day Brazil airpass ($530) to visit Manaus and up to three other destinations. Operators offering tailor-made itineraries to the Amazon include Journey Latin America (020-8747 8315, journeylatinamerica.co.uk), Far Frontiers (01285 850926, farfrontiers.com), Last Frontiers (01296 658650, lastfrontiers.com).
Where to stay:
The city-centre Hotel Monaco, from £52 per room per night B&B. The riverside Hotel Tropical at Ponta Negra, from £100 per room per night B&B. JLA has a three-night package at the floating Amazon Lodge, 115km from Manaus, from £285pp; also, an eight-night cruise on the Rio Negro from £1,264pp.
Further information:
Brazilian Tourist Office (020-7629 6909, brazil.org.uk). The Latin American Travel Association publishes a useful guide, available free by calling 020-8715 2913, or visit lata.org.
Country code: 00 55.
Flight time: Heathrow-São Paulo 11hrs 40mins, São Paulo-Manaus 4hrs.
Time difference: -4hrs.
£1= 5.94 reals.
