"Class V: Expert. Extremely long, obstructed or very violent rapids which expose a paddler to above average endangerment... swims are dangerous, and rescue is difficult, even for experts." - International Scale of River Difficulty

In the language of the Tongan people, its name simply means "Great River." The Zambezi begins at a spring in Zambia. Halfway through its course, it hits a gaping basalt chasm and conjures up Victoria Falls, a mile-wide sheet of thundering water that's twice as tall as Niagara Falls. Then the river quickly pulls off a second magic trick, squeezing its entire turbulent self into a 210-foot-wide gorge. At the base of this gorge, a quarter-mile below the falls and just over the border of Zimbabwe, there's a stretch of water flat enough to launch a whitewater raft.

I didn't know any of this when I stood in that spot myself one August day, three years ago. Sheer black walls soared overhead. Through the canyon's slit, I could see one thin slice of Victoria Falls tumbling 322 feet to the river. The water below me boiled green, and it was cold—cold enough for each of us tourists to be issued a black neoprene wet suit, the same kind that scuba divers wear. I thought I'd signed up for a rafting trip that any adventurous person would enjoy. I was wrong. This was strange, because I'm usually the sort of person who reads the warnings first. Now that it's over, I've been reading them in reverse, trying to figure out exactly what happened that day.

It was my first trip to Africa. I'd wanted to bounce around the bush in a Land Rover since I was four years old and fell in love with the movie Born Free on TV. And just thirty-eight years later, miraculously, my husband and I scored two spots on a budget camping safari to Botswana and Zimbabwe. I called a friend of a friend who'd traveled there, and she had one piece of advice: Go whitewater rafting below Victoria Falls. It was the highlight of her visit to southern Africa.

Patrick and I had been rafting before—once on the Green River in Utah, once on the Athasbasca in Canada. Running those rivers was like swooping along on little roller coasters, only with better scenery. In my imagination, I could already see the headline for my obituary, written in some distant future, beginning to take shape: Local Woman Rafted the Zambezi. That sounded so much better than She Always Paid Her Bills on Time, or as my parents sometimes put it when discussing my childhood, She Never Gave Us Any Trouble. I'd stuck with that script long enough. It was time to raft the Zambezi!

Patrick looked skeptical as he flipped through the pages I'd printed out from a Zambezi rafting Web site. "It says these are Class IV and V rapids. Haven't we just been on Class III before?" he asked.

I rolled my eyes at his killjoy attitude. I was pretty sure I remembered a IV on the Green. Besides, the brochure said that no experience or swimming ability was necessary, and that dozens of people went every day. So how hard could it be? And if a Class III rapid wasn't scary, mathematically a class V was just one and half times bigger, right?

When we got to Botswana, our trip's guide, Tim, agreed with me.

"Rafting is awesome, man. We flipped our boat three times," he said.

Flipping boats? Once again, I missed a warning. There were ample signs that no one should take Tim's advice. In fact, a truly wise person would probably do the opposite of anything he suggested. Tim was the ultimate safari guide for people on a budget. He had a shaved head and permanent pins in his ankle from a skydiving accident. He'd grown up hunting Cape buffalo with an uncle, and still thought anything risky was a terrific idea. While we slept in our tents at night, Tim crawled into a sleeping bag on top of our twenty-foot-high monster safari truck. I figured he either kept a rifle up there in case of animal attacks, choosing a high place from which to take aim, or he just considered the roof a safer place to sleep. Either way, I didn't want to know.

For two weeks, Tim sat behind the wheel as we bounced over rutted dirt roads in the national parks of Botswana. He pointed out giraffes stalking elegantly among the thorn trees, hippos yawning their snaggletoothed grins in the rivers and then vanishing under an explosion of water. By the time we crossed the border of Zimbabwe and drove into Victoria Falls, I was exhilarated with adventure and hell-bent on rafting.

The town had a lawless feeling straight out of the Wild West, but I didn't reconsider. Why question the judgment of local rafting guides, just because they live in a country where a collapsing economy is turning the currency into Monopoly money? At the bank, we saw a line labeled "Bulk Transactions" where people stuffed wads of Zimbabwe bills into boxes the size of washtubs. But when would we ever get to Victoria Falls again? This was the Zambezi—and tomorrow could be our only chance to raft it.

The next day, Patrick and I sat under some trees on wooden benches, listening to a rafting guide give the safety briefing.

"If you fall out of the raft, float on your back with your feet in front of you," he said. We'd already paid. We'd already signed a legal waiver, and been bused across town to the lip of Batoka Gorge.

"Now, this is what we call a worst-case scenario," the guide said in lilting, African-accented English. "If you are trapped under the raft, count to twenty. None of the rapids are longer than twenty seconds. If you get to twenty and you're still underwater, count again—you went too fast." He paused to laugh at his little joke. "The important thing is to play a part in your own rescue. Now, everybody find a helmet."

We climbed down decaying iron steps bolted into the cliff, deeper and deeper into the gorge. I started to sweat into my neoprene. The metal creaked underfoot like the doors of a haunted house. I could see empty air beneath my feet.

Ten minutes later, I stepped off the last rung and onto the riverbank. Seven slick-bottomed inflatable rafts waited there, already pitching on the river's low boil. Patrick and I stumbled into the last one and took the two back seats next to the guide, a tall, elegant man in his twenties named George. Our boat filled up with two couples in their sixties, including some Germans who couldn't quite understand George's accent. During the practice time, when he called "back paddle," they paddled forward. When he barked, "left!" they looked to see what everyone else was doing. The wife looked scared. Patrick looked worried.

The first rapid was named Against the Wall, a Class IV. The instant we hit it, I knew I'd never run one before. The raft tilted into a hole at a 45-degree angle, then dropped out from beneath us like the floor of an elevator. We smacked through a standing wave that shot up higher than my head. The hype is actually true, I thought. I had never seen a river like this one.

We ran an easy III, another big IV. George announced each new rapid by name, and told us which side of the river to swim for if we fell out.

"Our next rapidů Morning Glory, our first Class V rapid of the day. Its nickname is 'The Wake-Up Call.'"

A faint bell of irony rang in my head. I was getting a wake-up call?

"Right paddle!" screamed George. We hit the rapid, and then, inexplicably, I was spinning around inside a washing machine. It was puzzling.

When I'm not on vacation, I work as a video editor. This has given me an unusually good feeling for time, in all its minute fractions. Every second of television you see is actually made up of thirty individual photos, or frames. When thirty photos zip past the human eye in one second, it creates something poetic-sounding called "persistence of vision"—the optical illusion of movement. When I'm editing, sometimes I inch through my timeline one frame at a time, one-thirtieth of a second going by with each click of the mouse. I know, to a certainty, how far a runner's legs will pump in that fraction of an instant, how far a grizzly bear's head can lift to catch a jumping salmon. I don't know how long it took for our raft to flip over, but it happened so fast, I never even felt it. Later, George told us that a wave flung everyone on the right side of the boat over to the left, and our combined weight then flipped the boat over like a book slamming shut.

Freezing water spun me like a twig through complete darkness. Tremendous force pinned my arms to my body. I didn't bob to the surface like I should have in my sports-quality life jacket. There was no possibility of floating down the river, feet first, like the guides had advised. Was I in a whirlpool? I started counting. The flip happened without a warning, so I hadn't taken a breath first. By ten, my throat ached for air. At twenty-two, a triangle of sunlight flashed overhead, and I recognized the edge of the boat before it crashed down and extinguished the light again. Finally, I knew where I was: trapped underneath the capsized raft. I heard the guide's voice inside my head like a rewound tape, saying "Play an active part in your own rescue."

I kicked deeper, and out from under the raft, my head popped above water. The light felt as good as the air. The raft swept along the river upside down, about forty feet downstream. Just as I reached it, George dragged himself over the far edge and waved me off. By the time he muscled it upright, it bobbed forty feet downstream again. I swam through the churning green water and grabbed the safety line. Patrick materialized next to me. When he shook the wet hair out of his eyes, his face shone white.

George grabbed my vest in one hand and Patrick's in the other, and hauled us, gasping like fish, over the edge. The raft, now steered by no one, careened downstream. I turned to see a woman swimming up behind us. I crawled toward her, but my rubbery legs buckled underneath me.

"Help her," screamed George, pulling in another swimmer. Patrick and I grabbed the woman's vest and heaved, but we couldn't do it. George had to yank her in. The five of us clung to the sides of the raft, zigzagging down the river with no other people in sight.

"Where are the other two?" I shouted.

"Downstream," yelled George, grabbing his oar. "Paddle!"

We rounded a bend, and the rapid spit us out onto flat water. One of our lost team members waited for us on the bank, dripping wet.

"Are you okay?" I whispered to Patrick.

"No," he shook his head.

My stomach turned over. Patrick does not complain. He once broke a rib and didn't go to the doctor for a week.

"Something slammed into my foot. When it hit, I breathed in, so I was swallowing water the whole time we were under. I thought I was drowning."

We had capsized on the day's fourth rapid. That meant we had another half-dozen ahead of us—including three more Class Vs.

An hour later, we jumped out of the raft to walk around the Zambezi's one Class VI rapid, Commercial Suicide. Ten-foot high boulders crowded the riverbank. For another fifteen minutes I leaped from one giant chunk of stone to another in slick sandals, trying to keep up with the group even as the gap between us widened. By the time I got to the launch point, my legs were shaking even when I stood still, and George had already left with Patrick and our team. A different raft was sitting on the bank, waiting to pick me up.

"Hey, weren't you in the boat that flipped?" a woman asked in an awed voice as I climbed in. "We were watching. You guys really wiped out."

When we hit the next rapid, I leaned low over the boat's edge, dragging my paddle through the water with every muscle in my back, trying to personally shoot the raft straight through the whitewater so it wouldn't capsize. I must have leaned too far, because the next instant I was outside the boat again, clinging to the safety cord. I bounced through the rapid like a line of tin cans behind a honeymoon car. When the guide hauled me in afterward, the curious woman shook her head with sympathy. "You're really not having any luck today, are you?"

After two swims and a bout of boulder hopping, my arms and legs felt like Silly Putty. A dark thought formed in my head: If I fell out again, I would be too tired to swim.

The last rapid of the day was a Class IV—the Gnashing Jaws of Death. As the churning whitewater came into view, I heard someone pleading: "No, God, not again, please." That's when I discovered how eerie it is to hear your own voice when you're not aware you're speaking. I threw down my paddle and cowered on the bottom of the boat, eyes shut tight, gripping the safety line with both white hands.

And then it was over. The river smoothed itself out as flat as a kiddie pool. We paddled toward the bank for lunch.

"Can I go swimming here?" the man in front of me asked George. "I want to get wet again."

"Eh, this is not such a good place. The water is calm here, so it attracts the crocodiles. Yesterday I saw some that were three meters." Gee, that was something else the brochure had failed to mention. So if we'd flipped over in the Gnashing Jaws of Death, and I was swimming downstream again, I'd be dodging the gnashing jaws of crocodiles? I had edited some crocodile documentaries at work. They always led to discussions of Talmudic complexity with my boss. For example, was it okay to show the prey's entrails if you first cut out the moment of disembowelment? I was haunted by one shot in particular, of a crocodile munching on a severed antelope leg. It stuck out of his grinning teeth at a jaunty angle, with the pointy hoof at the end looking exactly like the tip of a toothpick.

"But I don't see those crocs today," George laughed, and pushed the man overboard.

After lunch, we climbed a near-vertical trail to the rim of the gorge. The guides at the top waited for us with a cooler full of Cokes in glass bottles. Soda bottles get refilled over and over again in Zimbabwe, and the worn glass felt soft in my hands, like beach glass. Apparently, I was not going to die today after all. I popped off the metal cap and drank it straight down, sweet and cold in my throat. It was the most delicious thing I'd ever tasted.

As George gave us a lift back to town, I asked him if Patrick's bruised and swollen foot was unusual.

"Oh no, this is nothing," he said. "We get a lot of broken legs, dislocated shoulders. People get so scared when the raft flips, they just keep holding on. Then the current pulls your arm out of its socket."

George's bluntness shocked me, even if it was just the three of us in his truck. In a place where people can be killed for speaking out against the government, telling visitors scary truths has got to be against the rules. So a few days later, we posed the same question to a taxi driver who held a graduate degree in tourism. He said that rafting the Zambezi was extremely safe because the local companies take every precaution: multiple rafts, safety kayakers, a helicopter to pick up the seriously injured. Was this just the party line, or the truth? By the time I got home, I was curious. How close had I really come to dying on the Zambezi?

There are several ways to drown in a river, and I found out about all of them while reading the American Whitewater Affiliation's grimly fascinating accident reports. The reports list a sobering variety of accidents under "causes of death," including head injury, suction pin, tree pin, keeper hole, and natural strainer (getting entangled in an underwater tree). Yet each of these accidents, I learned, is highly unlikely on the Zambezi. The river churns up the biggest rapids on Earth. But paradoxically, you can afford to run the Zambezi recklessly, because it's tough to get killed there. It's a river engineered by nature to be unusually forgiving.

Just three things create all the whitewater on the planet—constriction, gradient, and underwater features. A mile-wide waterfall that funnels into a 210-foot-wide gorge pretty much defines the gold standard for constriction. The Zambezi also sports a respectably steep gradient, dropping 400 feet during the one-day rafting trip. But the river's underwater features—such as boulders and ledges—lurk much deeper than usual, as much as 200 feet underwater. That leaves few places to hit your head or get pinned. And the river's V-shaped gorge cuts so steeply, nothing larger than a bush grows on its sides. This removes the danger of tree snags.

Although Zambezi rafters don't have to worry about these hazards, they still face the danger of taking a swim. In the parlance of whitewater rafting, a person who falls out of the raft, but manages to hang onto the boat, is called a short swimmer. A person who's separated from the raft is called a long swimmer. Putting this name to my accident in the Wake-Up Call made me feel queasy, especially when I read that "long swim" is the leading cause of death for rafters. But my research also revealed a counter-intuitive truth. The real gauge of a river's danger is not the size of the whitewater, or how easy it is to flip a raft or take a swim. The real test is whether you can recover from your mistakes. On the Zambezi, some of the world's biggest rapids are followed by calm stretches where rafts can pick up their long swimmers. In North America, Class V rivers aren't built that way.

In a much-publicized 1987 accident, a group of eleven advertising executives on a business trip went rafting on the Chilko River in British Columbia. Their boat hit a boulder near an infamous stretch of the river called The White Mile, spilling all but one man into the water. Its name to the contrary, the White Mile is actually three miles of solid rapids, all of them powerful enough to prevent a swimmer from getting his head above water. The result is called a flush drowning. On the Chilko, six of the men managed to rescue themselves, one by grabbing a tree branch as it passed overhead. The other five died.

All rafting involves risk. But when I added all the data up, I could only conclude that I was never anywhere near death—just on the best river in the world to get scared witless. Yet despite the power of rivers, the odds of dying while whitewater rafting turn out to be pretty small. In 1998, for example, 1.1 rafters died per 100,000 days spent rafting. That's compared to 1.6 people who suffered fatal accidents while riding their bikes, 3.5 people felled by scuba diving, and 15.2 people who met their fate doing something truly dangerous—driving a car. Does that make zipping over to the 7-Eleven for a banana Slurpy an unnecessary risk? It's a question every person has to answer for himself.

For me, I'd rather experience nature than challenge it to a duel—not least, because people who challenge nature often lose. I don't go backpacking to measure myself against the wilderness, or to prove something. I go because the words of John Muir resonate inside me: "Climb the mountains, and get their good tidings." I need to hear those good tidings, to melt away the honking horns and alarm clocks that fill my city life.

I don't want to fear nature, because it's hard to love something you're afraid of. I looked back at the Zambezi once before we drove away. The Great River roared blue and white through its winding canyon, its leaping whitewater hushed to a whisper by distance. I was shocked to see how beautiful it was. Because of that one glance, I'd like to go back and see the Zambezi again—but this time, without the hazy scrim of fear floating between us.

Title graphic: "Flipped" Copyright © The Summerset Review, Inc. 2011.