Sirens wail, and Rosa Estrada charges down a dirt path, down the side of a mud bank, then picks her way silently across the stinking, swampy earth.
"Get under the bushes!" someone barks in a whisper in the blackness of the night. "Immigration is coming!"
Twenty Mexicans scramble to the ground, crouching among thick branches and brambles.
"Hello, this is border patrol," booms a voice in English. Red and blue lights streak the sky overhead. In Spanish: "Are you Mexicans? It's too dangerous to cross the river. Remember your kids and families at home."
Ms. Estrada lies still, breathing quietly.
She is not on her way to "El Norte." About 700 miles from the US-Mexican border, she has paid $18 at a park in the central state of Hidalgo that offers a simulated experience of a migrant crossing.
Welcome to Mexico's take on adventure tourism, a five-hour trek that goes well past midnight. Residents pay to walk in mud past their ankles, balance on ledges – in pitch black – that drop steeply, and sprint across corn fields, kicking up dirt and rocks as they run from fake US border patrol officers dressed in camouflage.
The park was begun by the Hñahñu, an indigenous community in El Alberto that has been decimated by immigration to the US. Bernardino Martin, El Alberto's municipal leader, says the attraction has been criticized by some people as a training ground for would-be illegal immigrants.
But, he says, the purpose is to pay homage to those who must leave Mexico to earn money for their families, and, above all, to generate more employment so the rest of the community can stay put.
"It has been interpreted badly by some," says Mr. Martin. "It is misunderstood. This is so my neighbors prosper, so that no one else is forced to go."
"Come on, let's go! Be quiet, and turn your flashlights off," yells someone in the group taking the "tour" on a recent night. The pack walks the river's edge, then heads up a mountain and dashes into a gulch as immigration officers fan across the road ahead. "We have you surrounded!" the officers yell. "We will let out the dogs."
Ahead, another group of migrants, who are actually actors from the community, tries to run past the officers but are caught and threatened with deportation. Gun shots ring out. The pack behind them moves forward silently, until they find a tunnel and wait patiently.
"It's an adrenaline rush," says Alfredo Trejo, an accountant from Tlalnepantla, in the state of Mexico.
Some 3,000 Mexicans like Mr. Trejo have paid for this tour, called the Caminata Nocturna, or Night Hike, since it began two-and-a-half years ago. Far from picking up tips on how to cross the desert, Trejo and a group of family and friends came out of curiosity: "Someone recommended it; they said it was fun."
Others, like Estrada, feel a certain empathy. She's been on this "tour" three times, and each time brings a new family member or friend. "We get so immersed in our lives that we forget how much other people suffer," says Estrada, from Mexico City, who came with eight family members this time, including her 12-year-old son. "I don't want this to just be fun for him. I want him to take home the message."
"Run!" someone yells, and the group tears off to the road, piling into pickup trucks that barrel down the street and let out passengers at the next "safe" crossing.
Nestled in the mountains of Hidalgo, the town counts 2,200 residents, but more than half of those have left for the US. Those who stay make sponges and purses out of maguey fibers. They also run rappelling trips and offer camping in Parque EcoAlberto. But most people head to Las Vegas, at least temporarily, to find better jobs in construction.
Perhaps it's no surprise, then, that they have brought a slice of the culture of Vegas home with them.
The Night Hike is part adventure, part environmental lecture, and part history lesson. On a recent night the pollero, or smuggler, who is named "Poncho," leads participants in a rendition of the Mexican national anthem. The group stops next to the Tula River, and participants learn about the spiritual beliefs of the Hñahñu. "Poncho," who is really Alfonso Martinez, asks them to pick up two rocks: one with negative vibes and one with positive. The negative rocks are hurled into the river. The positive rocks are placed into pockets. "We want to teach about our community, so that it is respected," says Mr. Martinez, who, like all other residents, is giving a year of community service at Parque EcoAlberto. "Then we can start to address the massive inequality in Mexico."
But it's clear that most come for the thrill. The community tries to keep it as realistic as possible, though the park's employees, many of whom have crossed illegally into the US several times, say it's nowhere near the real thing. Will they build a wall if one is constructed across the US border? "No way," says Martin.
Eduardo Vazquez, Estrada's husband, says that he never wanted to go to the US. "I always thought you have to make it here first." But his brother crossed 15 years ago, and this experience has underscored the risks. "It gives you a social conscience."
He had another motive, he says, putting his arms around his son, Eduardo: that he never attempt the real thing by himself.
His ploy seems to have worked. Kids were fighting to keep pace in the back. One whined, "Aren't we there yet?"
As the tour winds down, participants lay down in exhaustion on the cold earth. They are dirty. One man had fallen into a rushing stream. Several were limping.
There was no attempt to simulate the entrance into the US. But these Mexicans got something even better: They got to go home.
• Ms. Llana is Latin American correspondent for the Monitor and USA Today.