The horizon to the north became a white, wet, rumpled tin foil, a hammered sheen that magnified and scattered the horizontal rays of the now red sun. There was one flame dancing in every wave. And the dimming of the evening light didn't quite calm down the world here on the cliffs among the owls—if anything the night seemed to amplify the otherworldly sound. One by one the stars emerged, and soon they too were jumping on the face of the water, abundant as the whitecaps, like fireflies a million miles away. It was Nietzsche who prophesied that the earth itself would become a place of healing. There is a deep emotional cure to be had out here, far from the lights of any town, where, even at sea level, the Milky Way seemed to be an extension of the blown salt spray. Time didn't so much pass as dissolve.

The edge of town is where the poor people live. For the most part, they are farmers and fishermen, but many take advantage of the seasonal migration of European windsurfers and other tourists; they run little cement-porch restaurants. I pulled up short at a café with precisely one table. The stereo was blasting Bob Marley into the darkness: "My feet is my only carriage." I sat down and ordered precisely one beer. Before I could pay for it, mysteriously, Senhor Ramos drove by in the washed Land Rover. The café belonged to one of his friends. He introduced me. Smiles. Good feelings. The beer was free. Whenever I travel, I get this impression: Total strangers are your true family. Your family is everybody in the world.

In the morning, everywhere people were raking, sawing, fixing things. Fishermen stood near their beached boats, talking about this very day. One or two of them soundlessly set sail.

Senhor Ramos carried "Imagens de Sattélites," and combined them with tide charts to determine the best times to travel up the coast. The images looked like slides of human tissue under the microscope. They showed the green puckerbrush agricultural plains of the Nordeste, which are fissured with blue rivers: Rio Ubatuba, Rio Camurupim, Rio São Miguel, Rio Parnaíba. Also visible were the white fringes of sand, a substantial foam riding the long, sweeping wave of the land, beaches wide enough to be photographed from space. "Senhor Anthony," said Senhor Ramos, "they were formed four hundred million years ago. No matter what, they will be here four hundred million more after we are gone."

Midway between Jericoacoara and the city of São Luís, the Parnaíba Delta is an unspoiled ecosystem of rivers, mangrove swamps, islands, beaches, and sand dunes. It has the size and majesty of the Mississippi Delta without the urban infrastructure to foul it up. Senhor Ramos dropped us at its eastern edge. He would meet us later on the other side.

Matthew Wakem Jeri, resembling a 1920s Mediterranean resort, has but a handful of cafes, restaurants, and nightspots. The village — and the big empty beyond — are environmentally protected.

We picked up the boat—the equivalent of a small Boston Whaler, with an outboard motor and a canopy to shield us from the furnace sun—in a small riverside village called Araioses. The pilot steered us in and out among the infinite labyrinth of emerald channels. Two men in a dugout canoe were foraging for açaí, an Amazonian palm prized for its antioxidant fruit. Jungle vines closed in, trailing vegetation in the water lilies along the shore. The mud was watery like gruel, and the water was muddy like pea soup. Fish rose in lazy circles. The channel became narrower and narrower, until the boat was whispering among the shallow reeds. I waited for the anaconda to drop on my neck. Then we ran aground.

The river was a river no longer. The motor was switched off. The pilot handed us a line; we stripped to our shorts, hopped overboard, and began to drag our vessel downstream. Some people might find wading in tropical slop, with who knows what sluicing between bare toes, unnerving. The human male will do anything if someone else does it first. After a few hundred yards of wading and hauling, the stream grew deeper once again, and we hopped back in the boat.

Toward noon, halfway through our delta traverse, we rounded a wide sweeping bend. Suddenly, rising overhead behind the deep jungle canopy on the bank was a golden sand formation much larger than a dune. The sand glacier reached the shore, sloping into the water as if it, too, were thirsty and hot. Between the blue water and the long smooth golden wall was a one-hut hamlet, with a thin smoke column rising from a cooking fire. A man and a woman squatted near it, intently focused on mending their fishing nets. One child romped along the shore with his dog. With the ominous power of the marching motionless sand behind it, the scene looked like a poster designed to warn of global warming. It was a visible parable, concise and precise: Those who have eyes, let them see.

Still shaken by this close encounter, we pulled ashore for lunch at the delta version of a voyagers' rest stop: A thatched roof shaded a few benches and tables. There was a spigot for drinking water and a canteen. As we stretched our legs, I noticed a monkey chained to a stake in the yard. One of his relatives, still enjoying his freedom, was crouched on a low bough directly overhead, deconstructing a coconut with his slender fingers and sharp teeth. I sat with the two of them: three primates eating lunch.

I shared my sandwich with the prisoner, all the while entranced by the dexterity and focus of the one who was free. He worked with a quiet frenzy at his task, deliberate as he peeled the tough bark to get at the pure white meat inside. The drive, intensity, and even the malice in his energy reminded me of jungle behavior back home. He was only a few feet away, and the frankness of his gaze was unnerving. I was looking in a fur mirror, where intelligence and malevolence intertwined. When we finished our meal, I bowed to the monkey in the tree and climbed back into the boat.

Matthew Wakem Cabins at Pousada da Buriti, near sand spit--like Cabure, come with their own hammocks.

The trip across the delta took five hours, but the lethargy induced by the tropical climate vanished once we found open water. The driver hit the throttle hard. For about six miles we crossed Tutóia Bay, with the Atlantic Ocean visible to the north. It was the great wide open, so clean even the mudflats were pure. There was no litter. Five razorbills squealed, left their fishing spots, and wheeled away. There were tropical flamingos so shockingly pink that they looked like lipstick, as well as plentiful oyster beds patrolled by great blue herons. We passed a solitary fisherman in his minuscule dinghy. The tea-colored sail was more patch than anything, a stained quilt of tears and repairs.

At Tutóia, a cluster of stuccoed houses in a palm grove, we soon spotted Senhor Ramos in his white Land Rover. In the dusk, we headed off for the tiny outpost of Caburé, where we were to spend the night.

The next morning at dawn, I was delighted to find that we were in a three-dwelling village, frail cabins on a spit of sand. I suppose it wouldn't be paradise if getting here were easy. Trees stood in the ocean. Black shorebirds called urubu breakfasted on shark. The Big Dipper hung upside down in the sky, as if it had been put back any which way after serving the rice for supper. After last night's strange, soundless thunderstorm, hermit crabs were rebuilding their tunnels, grain by grain. Four-eyed silver fish skipped away from the shore, like stones thrown by invisible children. Goats grazed in the salty bracken, tended by no one.

The Parque Nacional dos Lençóis Maranhenses is about the size of Rhode Island, forty miles by seventy, and composed entirely of sand dunes a hundred feet high. The geography here in early June is like nothing else on earth, because the rainy season fills every trough with water and the world becomes some kind of perfect contradiction of itself: like an M. C. Escher print, it is either a drowned desert or a sandy lake, depending on how the mind's eye frames what it is seeing. The pools carved into the sand fill with a green, earth-colored water, which in turn reflects the blue sky. Great white birds coast through, keeping their opinions to themselves. Their stark shadows seem as substantial as the mysterious creatures themselves. There are blown-grit walls ten stories high, on which fair-weather cirrus clouds trace their patterns as they comb the sky.

An egret cried in the starkness. It was the only sound I heard for an hour. One grass stalk emerged, thirty feet up the side of a dune, and the single blade tilted there, twitching in the relentless breeze. You can watch your own mind flounder for meaning. Clouds formed like thoughts in the soundlessness. They drifted, and as they passed over the oven hills, I could feel them as patches of low temperature. The stark purity of the landscape reduces the world to you and earth. The deprivation intensifies what remains. I walked for a while, and then I ran.

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