"The River and the Wall” from Austin director Ben Masters is one of this year’s must-see movies. And the South by Southwest Film Festival should be saluted for hosting its world premiere on March 9.

The documentary features stunning cinematography by John Aldrich, who captures the majesty of the Big Bend area of Texas as well as the lush, subtropical biodiversity of the Lower Rio Grande Valley.

The story follows five people who decide to travel the length of the Rio Grande by bicycle and canoe, until they reach the Gulf Coast. The characters include Masters, who is the team leader. But the cast also features Jay Kleberg, the associate director of the Texas Parks and Wildlife Foundation; Austin Alvarado, an Austinite who is a first-generation Guatemalan-American who graduated from Texas A&M and for the past five years has led commercial trips down the Rio Grande; Heather Mackey, who has spent two seasons on the Rio Grande, doing field research on wildlife and butterflies; and Filipe Deandrade, who immigrated to the U.S. from Brazil when he was 6 and is known for hosting the National Geographic Wild’s “Untamed” web series.

Throughout the documentary, we get to hear their personal stories and come to understand that each of them brings a particular perspective to the obvious central question of the documentary: Should a wall be built along the U.S. border with Mexico?

Kleberg, who grew up on a South Texas ranch, has concerns about the ranchers along the border. He and others learn that the U.S. will cede about 1 million acres of land to Mexico — and block vital access to irrigation water in some situations — if a wall is built along the border.

Masters thinks that the Rio Grande has never gotten the respect and protection that it deserves — and wonders whether there might be a better way to control our borders.

Mackey, as you might expect, fears what might happen to the wildlife along the river. If flooding occurs, will wildlife be trapped? If a wall is built, how will animals blocked from river access survive? And what about the environmental impact of the actual construction of a wall, which would require bulldozing in environmentally sensitive areas?

Alvarado marvels at the beauty of Big Bend — and the natural barriers its canyons pose to illegal border crossings. He makes a living on the river, guiding folks through majestic vistas. What if he were blocked from doing so by a wall? He also realizes that his own mother fled violence in Guatemala to find a better life in the United States, eventually being granted asylum and citizenship.

And Deandrade, who’s also an immigrant as well as a passionate photographer of wildlife, is probably the most affable of the bunch, at one point scaling a border wall with ease.

The documentary includes interviews with two West Texas congressmen, Republican Will Hurd and Democrat Beto O’Rourke, both of whom question the need for a wall. Both talk about how folks in Washington don’t understand the border and its complexity.

But it would be a big mistake to peg this as a political movie. It’s much more than that. In fact, it is a thrilling and gorgeous tale of adventure, with humor and flat-out wonder at nature’s beauty.

Producer Hillary Pierce is based in Austin and her film “Tower” won the Grand Jury Documentary Prize and Audience Award at SXSW in 2016.

The director, Masters, is best known for his documentary “Unbranded,” in which he and three friends adopt and train wild mustangs and ride 3,000 miles from Mexico to Canada. And Masters seems to be incredibly well-suited for cinematic adventures, as you’ll see in “The River and the Wall.”

“The River and the Wall,” which had its world premiere at the Rollins Center on Friday, screens again at 11 a.m. March 12 at the Alamo Ritz, and at 11:15 a.m. March 15 at the Paramount. If you didn’t see it at the Rollins Theatre, then your best chance of catching it will be at the Paramount March 15. And this film is a big reason to keep paying attention to the film festival after music takes the main stage.

(Update: The headline in this story has been updated to fix a misspelling.)

MORE SXSW

Captivating ‘Running With Beto’ relives instant history

Talk the Thrones panel nerds out on the end of Game of Thrones

Check out all our coverage