Iguacu, the world’s most spectacular waterfall

The 150m-long U-shaped cataract known as the Devil’s Throat is the largest and most impressive of the drops and marks the border between Brazil and Argentina.

Maybe, after the two-hour flight from Rio de Janeiro, my senses were playing tricks, but no, the others on my week-long trip to Brazil noticed something odd too after we landed at the small local airport. Namely, the sky was the most incredibly deep, vivid blue I had ever seen, as if extra pigment had been injected into it. The trees, too, looked more intensely green than I had ever seen them elsewhere.

Eder, our guide, sniffed nonchalantly as we drove along, the Jeep sending clouds of yellow butterflies up from the road. He said that he couldn’t see anything unusual, having grown up there, but those coming in from outside often commented on this phenomenon, which apparently is caused by the humidity, the moisture in the air generated from the falls and the lack of pollution.

Perhaps this had made us rather heady as we pulled to a halt by the pink-walled, newly refurbished Hotel das Cataratas — the only hotel inside the national park on the Brazilian side, and where you get exclusive access to the falls once the park gates have closed.

As we caught sight of the falls for the first time there was an audible gasp and a collection of phrases that started at “Gosh” and went up the scale to the unrepeatable.

It is their sheer size and the force and power that is so mesmerising, in a way that I never felt when I saw other waterfalls. In drier times (generally coinciding with the British summer), about a million litres of water tip over the edge — every second.

But after recent rains upstream, nine million litres per second were now spewing over the lip of the cliffs in front of us, sending thick misty clouds into the air into which small birds (great dusky swifts) darted to reach their nests that, almost unbelievably, they built on the rocks behind the tumultuous water.

We dumped our bags at the hotel and after a lazy poolside lunch of palm heart salad with acerola vinaigrette and locally caught surubim fish, wandered down a series of paths that lead from the front of the property, getting closer and closer to the falls, wetter and wetter. Coati — a type of racoon that has perfected its cuteness for gullible, snack-laden tourists — scampered nearby.

After a few hundred metres the path divides: left to the shop and loos, right, on a man-made gangway jutting 50m over the raging water, right up to the lip of the cliffs, where the brave get thoroughly deafened and drenched, and have a spectacular feeling of being enveloped by the falls. In the thrill stakes, no theme park rollercoaster comes close.

There are other ways to see the falls — by helicopter on a ten-minute flight, which allows you to appreciate the width as well as the extent of the rainforest, or by power boat, as we did.

Surging along the water, motor gunning against the power of the river, I can now officially say that I have squealed louder than a boatload of 15-year-old Argentine schoolgirls. I know because I was in direct competition and, believe me, I won.

The boats, whose drivers undertake two years of training, buzz right up to the falls, only metres away, which is almost like being placed in a sensory deprivation chamber — the water is so thunderously loud that you can’t hear, you are so wet that you can’t see and the sense of exhilaration — and fear — is overpowering.

The Hotel das Cataratas, run by Orient-Express on a concession from the national park, to which we retreated afterwards, is, in this noisy place, a real oasis of tranquillity, despite the ever-present background noise of the water less than a mile away, and the chirping of red-rumped cacique birds that nest near the pool.

The next morning the hotel’s resident botanist, Wilson Fernandes, took me out into the heart of the 185,000 hectares of dense forest, first by electric car, then by boat upstream from the falls, where we spotted howler monkeys, alligator, toucan and industrious armies of ants in their thousands. In theory, elusive jaguar, puma and ocelot lurk here, too.

Wilson told us about the fragile environment and how we have learnt from it. For example, the Guarani copied parrots that they saw eating clay to negate the toxins in certain berries, a practice now used to combat stomach aches and even rheumatism.

To get a perspective of the falls from the Argentine side, I took my passport and travelled through two border checkpoints and 12 miles (20km) to arrive about 1,000m from where I’d first started, on the opposite side. The viewing opportunities here seemed more commercialised, with lines of buses dropping tourists off at a small, narrow guage railway (built in Ross on Wye, near Hereford).

This chugs slowly for half an hour before you disembark to hike out on a walkway that juts almost a mile over the river and stops right over the cascading waters. The dusky swifts darted in and out of the misty clouds and all around people stood in awe. It really is an amazing, slightly scary, spectacle, and I’m sorry for doubting you, Mother Nature.

Need to know

Getting there Abercrombie & Kent (0845 6182211, abercrombiekent.co.uk) can organise an eight-night tailor-made itinerary that includes B&B accommodation in Rio de Janeiro, Iguaçú and the coastal resort of Buzios, transatlantic flights with British Airways and domestic flights with the Brazilian airline TAM, transfers and private excursions from £2,845pp, for two people sharing.

Further information Rooms at the Hotel das Cataratas cost from £255 per room per night, B&B (0845 0772222, orient-express.com ).