NEW YORK -- A man walked undetected across two runways and into a terminal at a busy New York City airport after becoming stranded on a personal watercraft in a nearby bay.

The New York Post reports that the 31-year-old swam to shore and then walked past motion sensors and closed-circuit cameras of Kennedy Airport's state-of-the-art Perimeter Intrusion Detection System. The $100 million system is meant to safeguard against terrorists.

The man climbed a perimeter fence and made his way to Terminal 3. He approached a Delta Airlines worker, who alerted authorities.

The Port Authority of New York and New Jersey is investigating. The agency says it plans to meet with the security system's maker this week.

The man was charged with criminal trespass.