"Lean right, lean right, lean right!" screams the instructor.
Too late. Wallop!
Blimey, it's cold in here! Thirteen thousand litres of water a second are suddenly pummelling my left earhole. My gold medal hopes are gone. I am up the Olympic creek without a paddle.
From Friday this week, the brand new White Water Centre in Lee Valley, Waltham Cross, Hertfordshire, will open to thrillseeking members of the public, conscripts to corporate jollies and to hen and stag parties.
Billed as "the legacy in advance", it is the first and only brand new Olympic venue to open to the public before the Games take place.
A ride around the rapids here is as close as most people will get to a taste of the Olympic dream. The centre has already taken over 3,000 bookings, at £49 per person. So what can those people who have made a booking expect to find at the centre?
Frozen toes and fingers. Even yesterday, on the hottest day of the year so far, jumping in to the fast flow in wetsuit, life jacket and crash helmet for the "swimming test" is a jolt to the senses. For those without the requisite canoeing or kayaking ability – most people, myself included – the standard option is a whitewater rafting trip around the rapids, swirls and eddies of the 300-metre course. A guide barks instructions from the back of the raft.
"Get down! Get down!" comes the order as we approach the opening rapid. But I don't react fast enough to prevent the water slapping me in the face as we nosedive. Thirty seconds later the raft is vertical on its left-hand side and two fellow passengers are in the drink. One of them has to be pulled out by the on-shore lifeguard and decides he's had enough. Our other soggy companion is dragged back on board and we start paddling again – sometimes forwards, often backwards, but mostly around in circles as we are spat through the artificial rocks.
After an entire morning of practice, our top time round the course is three minutes.
"Ninety to 100 seconds will be a good time come the Olympics," says David Florence, 28, a silver medallist in the C-1 slalom canoe in Beijing, who aims to go one better this time. He will have to navigate his canoe between about 20 pairs of poles hanging over the water, some upstream, some downstream, as quickly as possible. "It's a pretty spectacular course. Big waves, big stoppers, big drops," he said. "As good as anywhere in the world."
It is the sort of sport where home advantage might play a part. By next summer, when 12,000 temporary seats have been erected at the water centre 10 miles north of the Olympic Park, and the world is watching the fight for the four gold medals that will be handed out here, Mr Florence will have spent around 500 days practising on the course. The previous Olympics in Beijing and the recent Winter games in Vancouver were dogged by accusations of unfair access for athletes to the competition courses. Not so here – already the Slovakian and the Australian teams have been allowed on, and the French are coming next week. "We're open for 15 months, so why not let the others on as well," says Shaun Dawson, Chief Executive of the Lee Valley Park Authority, who are also responsible for the Olympic Velo Park and the hockey centre. "It's the Corinthian Spirit."
Rather like the placement of pins on golf greens, the course contains 1,200 moveable "rapid blocs". On the morning of the five-day Olympic competition, Games officials will arrive, shrouded in secrecy, and set them out, creating the unique formation of swirls, rapids and eddies that will form the medals' course, then decide where to hang the gates, further diminishing home advantage.
Nonetheless, Team GB is hopeful of medals in every category – the men's single and double canoes, and the men's kayak and the women's kayak. There have already been enough applications to fill all 60,000 seats.
"I'm excited, but I've been to enough big competitions in the past, I can cope," said Campbell Walsh, 33, a silver medalist in Athens in 2004 in the men's kayak.
"But I've got to get there first. There's only one place. There's a few of us after it. The trials are on 22 April next year. That's what I'm worrying about for now," he said.