DARIEN NATIONAL PARK, Panama — Stumps, chuckholes, vipers and foliage have fogged into a brown-green blur. Eight river crossings have soaked through the duct tape I've wrapped around my feet to avoid what's now happening.

Led by Hernan Arauz, the son of Panama's foremost explorer, I've come to retrace the old gold route through one of the most formidable slices of jungle in the hemisphere and witness the forces gutting this once-forbidden realm. With each step, blisters ignite and mortal ambitions falter.

No surprise. The Darien jungle has never taken kindly to drop-ins. In 1699, 900 Scottish settlers rushed headlong into the jungle. Indians or malaria killed most within months. In 1854, an American expedition began hacking through the tangle of deadly snakes and foliage in search of a canal route. They wound up lost and so hungry they ate their dead.

Even now, the 60-mile-wide Darien Gap is a chaos of snakes, caimans, crocs, narco traffickers, mercenaries, guerrillas and bandits. Despite these deterrents, the Darien — one of the Americas' richest wildernesses — has long been coveted, first by Spanish conquistadors driven by gold lust, and now by loggers and settlers.

Paradise and war zone

The conflict pits politicians and poachers against the indigenous Embera, Kuna and Wounaan who make the Darien their home, and environmentalists and eco-entrepreneurs who see forest green as the new gold, luring future flocks of adventure travelers and bird-watchers — there are almost as many species of birds in the Darien as there are in the entire United States and Canada.

The key threat at the moment is Panama's accelerating effort to lay asphalt and improve a stretch of road that dead-ends at this jungle. The Darien Gap is the only break in the 16,000-mile Pan-American Highway, a string of roads proposed by the United States in 1923 to whisk American goods south, and endorsed by the South American nations through which it now passes.

Laborers throughout Latin America leveled dirt and laid asphalt on what had been horse and pedestrian trails, but work stopped at the Darien's labyrinth of rivers, swamps, rain forest and mountains.

Once technology caught up to geography, other concerns stymied the highway, including fears that roadwork would lead to widespread environmental damage; that foot-and-mouth disease would spread north from South America; and that the highway would launch Colombia's drug lords on an expressway to U.S. consumers.

Despite such worries, the Washington, D.C.-based Inter-American Development Bank, the largest public lender to Latin America and an aggressive proponent of the road's completion, is financing upgrades of the dirt and gravel stretches leading to the gap.

Opening up trade

BRIAN VANDER BRUG / LOS ANGELES TIMES An Embera man plays a wooden flute, his hands dyed with blue "Jagua," a native tradition.

In about two years, road builders will finish blacktopping the final segments of the existing highway, luring ever more loggers, farmers, cattle ranchers and developers. Proponents say this not only will aid the nation's progress but will also improve the lives of the Darien's native people by making it easier to sell their goods in Panama City, increasing their access to educational opportunity and health care — and generally extending the virtues of civilization.

Environmentalists warn that the incursion will wipe out the wildlife — and eco-adventure — that many see as Panama's true economic hope.

Already, trucks stacked with logs 30 feet long and thicker than BMWs rumble by en route to mills closer to Panama City. "Every log that you see coming out represents the end of life for not only the tree itself but also for a myriad of insects and birds and to plants that were attached to it," says nature guide Hernan Arauz, machete in one hand, shotgun in the other. "It is a big loss. A big loss."

Hernan is the son of legendary explorer Amado Arauz and the late Reina Torres de Arauz, the country's most accomplished anthropologist. The stocky guide remembers his cleanshaven father heading off on expeditions and returning from the jungle thinner, his beard full and brimming with stories. "I have many recollections of Indian chiefs coming to our house to talk to my mom about the issues they were dealing with on the indigenous reservations."

Hernan Arauz scrapped the cushy life of a career diplomat 15 years ago to become a naturalist guide and follow his parents into the jungle, where, in his own way, he continues his parents' efforts to increase understanding of the Darien.

Luring few tourists

BRIAN VANDER BRUG / LOS ANGELES TIMES More than 500 species of birds make their home in Panama's Darien National Park.

Currently, fewer than 700 tourists visit Darien province's rain forests each year, spending an estimated $300,000. As many as 700 visitors a day may traipse about looking for monkeys and quetzals in one of neighboring Costa Rica's much smaller national parks. Ecotourism in Panama brings in $20 million a year, while Costa Rica nets $360 million annually from travelers visiting wild places. Arauz believes Darien National Park could attract 500 visitors a day without harming the environment.

At 43, Arauz has crossed Panama from the Atlantic to the Pacific 11 times on foot, following the path of Vasco Nunez de Balboa, the first European to gaze upon the Pacific, in 1513. Succeeding conquistadors built a gold route that wound 6,000 miles across land and sea from the Holy Ghost Mine in Cana, a jungly valley at the heart of Darien National Park, to the treasuries of King Charles II in Madrid.

Arauz's course snakes 58 miles up the Tuira River, a river that is, depending on the season, the color of either crankcase oil or cafe con leche, and tranquil or raging. When we leave the river, we will hike another 28 miles through jungle into Cana. Ahead of us are the very dangers that killed conquistadors and their African slaves by the score — hidden fer-de-lances (the deadliest snake in the Americas), diseases and parasites, among them malaria and botflies. And Balboa never had to worry about the human hazards that now spill over from Colombia: government troops and homicidal thugs working for land barons or drug lords.

Follow the river

BRIAN VANDER BRUG / LOS ANGELES TIMES A man unloads plantains in the small port at Yaviza on the Tuira River in the Darien province of Panama. Most cargo from the area travels by boat because the Pan American Highway in the area is not paved.

At dawn, Arauz trips the motor, and our fiberglass boat starts skimming up the Tuira. Scenes of plastic refuse, tin roofs and motorized boats soon give way to stretches of wild riverbank broken by thatch-roofed homes and Embera kids leaping into the river. Overhead, vultures hover.

Late in the day, the frontier town of El Real, just outside the protected Darien zone, appears on the western bank. The Spanish built a garrison in this sweltering backwater to protect gold from the Holy Ghost Mine. Today, the hamlet covers eight blocks in a grid pattern, but there is just one vehicle, a truck, among El Real's 1,185 souls, most descendants of Africans whom conquistadors had forced to work the mine.

A typical home seems made of little more than faded paint and a corrugated tin roof. The town's mayor, a former ranger, says he is disgusted that the government pays for only 11 rangers to protect a 1.4 million-acre park. Four times that many are needed, he says. And they need walkie-talkies. And vehicles. Part of the $88-million loan that is paying for road improvements is also supposed to pay for the park's needs. The mayor has gone to Panama City with requests for money, but so far he may as well be shouting into the forest, he says.

In the morning we set off on a route used by an English outfit that worked the Holy Ghost mine from 1894 to 1921. Back on the river, we glide past eternal scenes. Women dunk dirty laundry, pile it on rocks and beat out the dirt with clubs. Children swim, some dark blue from foot to chin from the juice of jagua nuts they brush on themselves to heal insect bites.

Three and a half million years ago, on what today is a portion of the Tuira, a natural canal connected the Pacific and Atlantic oceans. Eventually, shifting tectonic plates created a mountain range that would close the waterway and others like it in the Darien. The jungle became a crossroads and chokepoint for the continents' wildlife, as tapirs, bears, cats, deer and a species of extinct horses made it across the waterways going south, and monkeys, marsupials, armadillos, anteaters, sloths and a type of gigantic carnivorous bird went north.

Sharp contrast to jungle

Today Panama City, the nation's capital, is the landscape's dominant crossroads — all gleaming skyscrapers, fancy restaurants and streets crawling with SUVs. These two Panamas know little of each other, as we're reminded at Union Choco, the next community upstream. Most houses here are like those built by Embera and Wounaan generations ago. They rest on stilts, have stick walls, thatch roofs, and you enter by way of a log with steps hacked into one side.

It's the kind of scene that rivets adventure travelers, whom the cash- and job-strapped Embera would like to see more of. More tourists mean greater demand for guides, boatmen, porters and cooks, and more buyers of handicrafts and produce.

Without work, some Embera wind up selling their timber rights to loggers. Manolito Kaisano, a Union Choco shop owner, explains what typically happens.

"The lumber companies come through the communities and offer this and that, and the communities go for it," he says. "But they always cut more than was agreed and pay the minimum. They promise houses, roads, public services, schools, and they promise us $10,000 or $12,000 for 3 million board feet of wood. They give us a portion of the money and build nothing."

The village echoes with stories about another Darien. Diagonisia Zarco, 40, remembers when the forest flanked Union Choco. She misses the monkeys and deer she saw as a girl. The forest is far away now, she says, with a wave toward Colombia.

Another Embera, Nabel Cabezon, offers a similar lament. "Upriver, I have seen a jaguar. A big black one. At Paya. There were a lot. That was a long time ago."

As we're leaving the village, Arauz reflects on the changes he sees. At such moments, his facial expressions can be almost frightening. "I get very angry," he says, "seeing how the Panamanian economy ... places value on felled trees and does not recognize the terrible damage to an area suffering constant deforestation.

Raw nature

The next morning we begin a two-day, 28-mile uphill trek. It's hot. I'm on Day 3 of the PowerGel diet, thanks to dysentery. The open sores on my feet don't help.

Still, the jungle commands attention. Leaf-cutter ants march along carrying pieces of leaves that resemble sails. Acardium trees, from which the Embera make dugout canoes, tower into the canopy, and enormous root buttresses sprawl across the jungle floor. The forest's aromas range from alluring to repulsive.

Five hours after leaving Boca de Cupe we come to a mossy sign nailed to a sky-scraping tree: Darien National Park. As we begin a nonstop push for Cana, a kettle of broad-winged hawks migrating to the United States from South America passes overhead. Flying alongside them for a minute or so are two great green macaws.

The wind moans as tree trunks rub together. A damselfly flickers past. At times the rain forest seems wired, with hordes of cicadas buzzing like high-tension lines.

We reach the old Spanish site of Cana in the early evening. Jungle growth cloaks rusting locomotives and ore cars. The legendary shaft worked by slaves for 130 years and Jamaicans for another 30 years is now a silent square hole in the earth with the carcass of a jaguar at the bottom.

Four species of macaw fly overhead with regularity, and at the edge of a grass airstrip, we see the latest contingent to seek treasure in the Darien: Eddie Bauer-garbed birders peering into spotting scopes. It's a sight for sore guides. "One of the most comforting and encouraging sights that you can see today in the Darien is the presence of eco-tourists," Arauz says.

Noted for birding

Cana today is one of the top 10 birding sites on the planet. In recent years UNESCO declared Darien National Park a World Heritage Site and a World Biosphere Reserve. There is no place like it, because it is here and only here that one can see South American species — the red and green macaw and the red-naped tamarin — at their northernmost range, and North American species — including the gray fox and the coyote — at their southernmost range.

The fox and coyote, Arauz says, are just now entering the Darien — "a sign that this great inter-American biotic exchange still goes on today."

Ants half an inch long parade past. Brilliant blue morpho butterflies dart and flutter around us. Howler monkeys, crab-eating foxes and white-fronted nunbirds see us before we can see them.

They'll be seeing more and more of our species soon.

Soul-searching continues. Marco Fierro, a Panama City-based environmental consultant, approved the new road work. Now he laments his decision. Too late, he admits. "There's no stopping the road. Contracts have been signed."

This fact weighs on Arauz. "The worst enemy of a rain forest is the road," he says. "We should look at the Darien rain forest as a highly productive mine of eco-dollars. That is really the value of it."

But hardly the measure of its worth. "If the Darien were to be lost," he adds, "Panama would lose its soul, because nature is the base of everything."