There is a deafening roar, a wall of white blinding mist and then everything is wet.
A puddle of water laps in my seat and an earthy bitterness pricks my tongue, but I am in such raptures I can't close my mouth.
By the time the voyage is over my knickers will need to be rung out and my hair will be dripping but I don't care.
On the bus to Iguazu Falls an old Argentine man described his country's most famous landmark thus: "Standing at the waterfall you feel God.
God is flowing through the water," he said, wide-eyed and gesticulating as a blood vessel bulged from his forehead.
I don't know about God, but I can certainly feel the almighty force of mother nature as I am buffeted by a tsunami of water on a speed boat that is little more than a rubber dinghy.
To explore South America's most renowned cataracts I have joined an adventure safari to the base of the colossal waterfalls.
Boarding downstream on the Argentina side of the Iguazu River, all was quiet and serene.
The river was fast-flowing but there was no sign of the tumult ahead.
Soon we were ski-jumping over frappuccino rapids, creamy torrents burst from the riverbank and an impenetrable mountain of crashing water lay dead ahead.
The boat edged tantalisingly close to where the falls explode and then there was a tremendous assault on the senses.
First, the thundering noise, the blinding spray, and then the drenching backwash of water.
And it's a lot of water.
More than an Olympic-sized swimming pool of the stuff crashes down the falls every two seconds, and that's on an average day.
Today the river is so full boat crossings to San Martin Island have been cancelled and thrill-seekers risking the walk to the boat launch look in danger of being blasted off the path.
Much of the riverbank has been swallowed by opaque cascades and the grey sky, falls and mist have melded into a massive atomic cloud of vapour.
It is an awesome spectacle.
Iguazu Falls, meaning "great waters", are located in the northeast corner of Argentina and slice through the Brazilian border.
They were formed 200,000 years ago by a geological fault that opened up the Earth, sending the Iguazu River tumbling 80m over a half-moon crater of sandstone and basalt.
Already a Unesco World Heritage Site, Iguazu is now vying for another accolade, making the short-list for New7Wonders of Nature status.
Twenty-eight natural wonders from around the world have made the cut and the final seven will be determined next year by a global vote of more than one billion people.
Iguazu has been awing crowds for years but the attraction is also an amazing feat of man-made ingenuity.
The highlight is at the crest of the falls, known as the Devil's Throat, where a perilous catwalk is anchored into the raging current.
Here sightseers stand suspended centimetres above the lip of the biggest waterfall and can peer into the frothing abyss.
A network of other viewing platforms ladders across the river and islands, taking in many of the more than 200 cascades that make up the upper and lower falls at Iguazu.
It's a full-day adventure, and that's just on the Argentina side.
On the Brazilian side of the river the viewing areas are a little further from the action but afford an incredible panorama of the whole tiered display.
And there are still plenty of opportunities to get wet.
When I cross the border, the main viewing tower is like a lighthouse being pummelled by an inverted ocean of water.
There is a runway to the centre of the river, but today it is a gauntlet, the water splutters and sheets horizontally over the rails, like an industrial bio-hazard shower.
The traders selling plastic ponchos are doing a roaring trade but man-made fibres are little contest against the fury of nature.
And who needs them anyway?When you come this far it's hard to resist diving in head first, metaphorically speaking, and soaking up the experience.
When your shoes are squelching and your entrance ticket is sodden in your pocket you know you have felt the power of Iguazu.
Just be sure to bring a change of clothes. And don't forget a spare pair of knickers.
