“Every mammal on this planet instinctively develops a natural equilibrium with the surrounding environment, but you humans do not. You move to an area and you multiply and multiply until every natural resource is consumed and the only way you can survive is to spread to another area. There is another organism on this planet that follows the same pattern. Do you know what it is? A virus. Human beings are a disease, a cancer of this planet.” –- Agent Smith, “The Matrix“

Agent Smith could have been talking about the “morning after” footage in “Gringo Trails,” a new documentary by Pegi Vail and Melvin Estrella. The camera wanders down Thailand’s Haad Rin Beach after the Full Moon Party. The beach is littered with trash — water bottles, clothing, plastic bags -– and crashing partiers. Garbage sloshes up on the sand in the gentle surf. This beautiful stretch of sand, once completely unknown to travelers, is now punctuated with rubbish. The film illustrates some hard truths about mass travel, but I found it especially painful to watch this segment. It was embarrassing to the see the awful disregard for this once beautiful place. And it was sad, a weighty head-shaking sadness that left me questioning the results of my own backpacker traveling days. Was I this unaware? Did I spread the virus?

“Gringo Trails” looks at the impact backpackers have on places like Haad Rin. How were these places “discovered,” and how did they change as a result? What effect does the influx of tourists — the kind who insist they are not tourists — have on the environment and on the people? Are these travelers even aware that they leave their fingerprints all over the economy, the culture and the ecosystem of the places they visit?

Vail and Estrella aren’t issuing a blanket indictment of backpacker travel — Vail was a backpacker herself in the early 1980s. Her message is more educational. “When this type of travel started, we were completely unaware of the implications. But now, 20, 30 years later, we know. We know what happens, and we can share this information so it doesn’t happen in other places.”

The movie opens with the story of Yossi Ginsberg, an Israeli backpacker who was lost in the jungle near the village of Rurrenabaque, Bolivia. In 1985, Ginsberg wrote a book about his misadventures and how he was rescued. Rurrenabaque had been a small hub for adventure travelers, but Ginsberg’s book launched an influx of Israelis seeking their own version of that adventure.

The travelers in “Gringo Trails” seem to think of Ginsberg’s story as an amusement park ride, as something they should be able to access. An Israeli girl says, “Everybody wants to experience the life of the jungle . . . to have a little touch like in the book.” “I’m Indiana Jones,” says a Swedish backpacker from the seat of a crowded motor canoe. Ginsberg was lost. His life was in danger; he was lucky to be saved. And now travelers — inspired by his story — can pretend they are having a facsimile of his experience. With meals and camping and guides included.

The movie takes us to a number of different destinations, showing the change that backpackers bring when they open new regions to increasingly organized tourism. We see the archetypal travelers we’ve met in our own adventures: the traveler vs. tourist snobs, the beach hippies, the partiers. There are stories from Pico Iyer, Rolf Potts, Holly Morris and Prince Sangay Wangchuk about the tension between travelers’ values and the native values of the places we visit. Vail and Estrella take us around the world and show us, in archival footage shot over many years, exactly what we’ve done to the planet by being everywhere on it.

“The idea of adventure, to be in the jungle and surviving is an idea that spans a lot of different cultures, but most people don’t take it to the extreme,” says Vail. “They like the idea that they’re having this adventure, that they’re somehow surviving in the jungle . . . but I don’t think they think it through. They don’t really want to have that experience. People conflate the images. . . . it’s the completion of all these stories in the media that affect what our destination perspectives are and what we’re looking for.”

There’s a painful tension between the desire to have a great adventure — to share that adventure — and to protect a place as it is when we find it. In “Gringo Trails,” Costas Christ, editor-at-large for National Geographic Traveler magazine and an early advocate of ecotourism, tells the story of “finding” Haad Rin in 1979. He admonished some fellow travelers, Germans, “Whatever you do, don’t tell people about this place.” In 2013, an estimated 30,000 people attended the Full Moon Party on Haad Rin Beach. Christ’s Germans may not have told, but the story got out.

In “Gringo Trails,” Vail travels around the world to show how travelers are affected by the romance of packaged travel stories in the media as well as through word of mouth. Adventure becomes a commodity. “It’s good value,” says Lina Brocchieri about her excursion to untouristed and exotic Timbuktu. She’s presumably speaking of the cocktail party caché she gains in mentioning her travels to this place so weighted with the extraordinary. But the reality of her experience is sobering and enlightening. Her presence makes no sense to the locals, and she begins to wonder why she is there.

“Romanticization is writ large . . . versus the reality of how people are living, the poverty,” says Vail, speaking of our preconceived notions as travelers. “I was hoping the film would have people think before they go.”

The film offers up some suggestions but no easy solutions to the change we invoke by merely being present in these faraway places. Ecotourism. Government regulation. A discussion of Bhutan’s visa program shows how the country has chosen to restrict travel to protect its cultural heritage. Ultimately, though, the responsibility lies with us as travelers. Our “high-value” experiences cost us money, but what’s the expense to the places we choose to visit? How do we reconcile our romantic images of the world with the truth of what our presence in those places means?

Adventure travelers and backpackers are often the front line. We crack these places open to the rest of the world. At our worst, we are looking for easy social mores, cheap booze, accessible drugs and a line on our résumés. How strange that we should fall into the role of de facto ambassadors for these places. But at our best, that’s what we are — ambassadors. “Gringo Trails” leaves the traveler shouldering the weight of that responsibility. How are we going to interpret the stories we hear, and what stories are we going to tell?

“I like seeing the changes,” says Vail, “in how people apply what they have learned. You can do something. Instead of just traveling through and gaining experiential capital, we can give back. It’s middle-class, upper-middle-class, travelers, if they say they’re on a budget or not. So there’s disparity between classes and cultures. Now, I think a lot of people are coming back are doing something.”

“It’s a fine line between the joy and the incredible experience of travel with the reality of local lives. I hope we can enjoy the film, think about why we love to travel and also, think responsibility. The hope is that it’s opening a conversation. This is a tremendously important topic. And it’s urgent, given that we’re all over the place in the world.”

“Gringo Trails” premieres on October 19, at 8:30 p.m. in the American Museum of Natural History during the Margaret Mead Film Festival. There’s a screening at North America’s largest environment film festival, the Planet In Focus Environmental Film Festival in Toronto November 21-24. Additional screening dates will be available on the Gringo Trails website.