Transcript for Tracking the Treacherous Journey Across US-Mexico Border
When people swim across the Rio grande to come to America, they are wading into dangerous currents, open sewage, and often water snakes. Tonight, a look at the crisis along our southern border that you've likely never seen before. Here's Jorge Ramos from our sister network, fusion. Reporter: I'm on the Rio grande. Mexicans call it Rio bravo, the furious river. And this day it feels like a -- patrols, masked men on fast boats carrying high-powered firearms. They're ready for anything. And so am I. The second they go out of their house it's a very dangerous journey for them to cross illegally into the united States. Reporter: The Rio grande, 1200 miles of water between the U.S. And Mexico. The point of no return. 33 immigrants have died crossing over just in the past nine months in the Laredo area alone. Murray Salas is the supervisory agent for the border patrol in Laredo, Texas. The currents are very strong, especially underneath. If there's any rocks, any debris, any potholes when people are crossing, they're going to Payne. Once they panic, they're going to get in trouble. Reporter: It is clearly very dangerous for an adult. What would it be, a river like this, for a kid? It would mean death. Reporter: Since October last year an estimated 57,000 children have made the treacherous journey from central America headed to the united States. Double last year. Increasingly, the river has become a dangerous cross-roads. This 15-year-old from Honduras crossed the river just a few days ago. Were you scared of swimming the river? You were scared. Orbin, which is not his real name, says he escaped from his violent home town, San Pedro sula, to make his way to the border and into Texas. His mother lives in Florida. It took him 25 days traveling alone with no help. Why did you leave Honduras? Orbin told me he had to leave because the gangs threatened to kill him. This is the way that immigrants come to the united States. And you can see all the traces, once they get into the water, as you can see, they use all these kinds of plastic bags to protect what they have. The little that they have. Reporter: To find out what these central American immigrants endure under the supervision of many border patrol agents, my producer and I decide to cross the river. In some places the river can be as wide as 600 feet. Strong undercurrents push us at least 200 yards from our starting point. And we remember the agent's warnings about debris and other dangers. We swim all the way to the Mexican side and back. Just imagine what would it be for a kid, 8, 9, 12, 13 to try to cross this river by himself. Reporter: It takes us about 20 minutes. For those who make it to the other side, this is just the beginning of an arduous journey. Many will end up in detention facilities to be deported. As for or bin, he's trying to avoid deportation back to Honduras. He's 15. He's incredibly courageous. Yes. He did it all by himself. What happens to him if he goes back? He was telling me how his friend was also threatened as he was to join the gang and because he did not want to join the gangs they killed him. So that's what really made him snap and say I have to do something because I'm next if I don't join the gangs. Reporter: A deportation for Orbin would be a death sentence. Which is why they continue to risk crossing the furious river. For "Nightline" I'm Jorge Ramos on the Rio grande.
This transcript has been automatically generated and may not be 100% accurate.