You may have heard stories of friends accidentally sneaking banned items through airport security — pocket knives, nail files, larger-than-regulation-size bottles of liquid — because they simply forgot they had them and TSA didn’t detect them at the checkpoint. An inadvertent breach of security occurred at one of the nation’s largest airports a couple months ago but highlighted the potential for even more dangerous vulnerability.

ABC News reported that Daniel Casillo was jet skiing on New York’s Jamaica Bay in August when his water-craft failed. Being “pitch black” outside at the time, Casillo said he saw a lighted tower in the distance and swam toward it. ABC stated that reaching the light took a three-mile swim — Casillo was wearing a life jacket — a treck through marshy ground and climbing a chainlink fence.

Daniel Casillos Inadvertent Breach of Security at JFK Airport Leads to Changes

Casillo would have jumped a similar fence at JFK airport. (Image: ABC News screenshot)

The 31-year-old might not have known exactly what he was going toward as he made his way to the light, but when he reached the 8-foot fence, he quickly found out where he was. He breached the security at John F. Kennedy International Airport. Here’s how ABC described what happened next:

Cold and disoriented, Casillo climbed the 8-foot fence, but nothing happened. Despite climbing the fence and violating the law, Casillo remained undetected and headed toward the control tower.

“That was the only thing lit up that I could go to,” Casillo said.

Casillo walked across two runways past security, cameras and motion detectors that the airport recently paid millions of dollars to install.

“I figured I was going to be on cameras,” he said, “that somebody is going to pick me up and maybe a helicopter is going to come or a police car.”

Still unnoticed and wearing his life jacket, Casillo entered Delta’s Terminal 3, dripping wet when he finally walked up to a cargo worker.

Watch ABC’s report:

At this point, Casillo was arrested and charged with a trespassing felony. He plead guilty to a misdemeanor.

As for the security breach, the Port Authority told ABC News it ”took immediate action following the incident to increase not only Port Authority police patrols, but also increase our civilian patrols of the airport perimeter. Those patrols are 24/7 at all four airports.” It is also reviewing contractor Raytheon’s system that was supposed to detect such a breach. ABC reported that the security system cost $100 million.

Daniel Casillos Inadvertent Breach of Security at JFK Airport Leads to Changes

Daniel Casillo during his interview with ABC News on airport grounds. (Photo: ABC News)

Overall, Casillo said breaching airport security was not something he meant to do, but he feels he “exposed something really important.”

Read more details of the incident on ABC News here.