The Rio Negro, I am told, is a river like any other.
This is Brazil, the jungle, so it keeps tropical fish. It's an air force base for brightly colored birds. And like the Amazon, which it empties into, it supports our boat.
But the Negro that I know a little now isn't made of water. It's a river of beer. It is lightly fermented thanks to the compost of leaves and insects along its banks.
Drinking a glass is one thing that isn't tempting during my week-long cruise here on the Tucano, a riverboat run by Ecotour Expeditions. Negro means black, and we get intimate with its cocoa richness when we take showers and brush our teeth.
Our boat trip into the jungle begins in the city of Manaus which, if you ask it, will tell you about the days when rubber was still harvested from trees. Plantation owners tapped into their fortunes near the town and gave it dashes of elegance and art.
The Tucano, which is moored here, looks like a model of a Mississippi steamer. A bath toy at first glance, it has room enough for nine elegant cabins which are paneled with forest woods and polished up carefully with wax.
One of our guides, Edivam Regis, explains our route. We are heading upriver on the Negro because it is wilder and less settled than the Amazon itself. Guide number two, Alzenir Sousa, a local who was born in the jungle, goes to work in the dining room setting up a vegetable quiz.
A table is laid out with alien blobs. Blobs that have been picked from trees that we are floating past. Not one of us can guess the names.
This red pincushion, says Sousa, contains a lychee nut.
(Whack! Sosa is correct.)
This bowling ball, Sousa insists, is, in truth, a pod of Brazil nuts.
(Crack! Like a piñata, nuts and shells spill out from inside.)
The Tucano's two canoes are loaded up at 6 a.m. for our first morning ride. The sky is low and soft. Here are dots of insects buzzing low, and V's of bird wings I have never seen.
A screech shoots from a palm where two of the birds have landed. "Festive Parrots," whispers Edivam. "Festive," he says, "because of all this noise."
Festive, I think, because they are a party green.
Over the canoes comes a flying rainbow. No body. Just a beak with wings.
Froot Loops cereal got it wrong. Their box bird is fat and jolly. This guy is arrow lean.
Now come dips and drops of monkeys at the tops of trees. Suddenly a blast of breath from near the canoe. A river dolphin pops up. It is pink as sunrise, and swims along with us back to the boat.
That night Sousa tells us a story. It is dark on deck and there is only silence, his soft voice and stars.
"The dolphin," says Sousa. "There is the gray one. And there is the pink like you see today. Nobody like the pink one. But they respect him. The Indians do not kill him, they do not eat him. This is like eating a person."
You can hear our breathing as Sousa explains. The Indians, he tells us, say this: "The pink dolphin can become a human. He will wear white clothes and a straw hat. He may appear at a party. He may come up on board."
We look around our circle and see dolphins, dolphins, dolphins in our chairs.
Days go by in a blur of animals and fish and trees With leather puttees in place to ward off snakes, we walk on shore beneath a canopy of wild banana, kapok and cocoa. Sousa slices into a rubber tree which cries white tears.
A wasp nest hangs like a bell. Aztec and bullet ants work on projects. Mosquitoes whine. We slap and scratch.
When we go out in the canoe at night our searchlight ignites animal eyes along the bank. "See that?" asks Sosa. We see pinpricks of white, then shapes of wings. A bird. In another tree there's something coiled. A hose. A boa. Fat and asleep on a branch.
Slash! Floosh! Edivam has jabbed his hand over the side.
Something's got him.
No, that's wrong. He's picking up -- wet in the light beam -- a reptile prize. A yard-long caiman. Gripped behind its head it's still, and we take turns touching the skin.
Catching caimans is a guide's idea of fishing. For us, it's paddling at dawn with hooks and wooden poles. We putter around, hunting and fearing piranha. Our bait is steak. Someone gets a strike. The line is bitten. No one is there.
Finally, we are finding fish. "I've got a big one," shouts Zona Hoffman from Needham, MA. Her husband stares. She's 68, and has never fished before.
But Hoffman is right. She pulls up a black piranha. It thrashes. It's maybe 10 inches long. Edivam grabs it, flattens its gums. We see the teeth of a saw.
Next day the Negro has another challenge. Instead of dangling in bite-sized cubes of beef, we will be the bait. We land the canoe on a white sand beach. It is time for a swim.
The water is still India pale ale. And we are wary, at first, of what is hidden in the river. The guides are swimming too. They tell us piranha will not like our size, our splashing. And slowly, like a snake uncoiling, we relax, stretch out.
We dive. We dominate the water. We do our floats and strokes.
We are strong, we think. When sunset comes, we towel off and have our dinner of fish. It is a night of river victory. Of confidence.
Once the stars come out on deck we sit in silence in a circle. The jungle seems asleep. There is almost no breeze.
I do not know when I drop off. But I am dreaming dolphins: gray and pink.
I am awakened by a splash. I run downstairs.
Around a corner, I almost catch him. It is a man we haven't met. He is from the river. He is wearing white.
And -- I can almost see it in the dark.
A wide straw hat.
Peter Mandel is an author of picture books for kids, including his read-aloud bestseller: Jackhammer Sam (Macmillan/Roaring Brook), and his newest about zoo animals passing on a very noisy sneeze: Zoo Ah-Choooo (Holiday House).