Karl Besas, 24, was boating with friends Friday night when the group went for a swim, but Besas never returned to the boat.
Halifax County officials say Lake Gaston is 35 to 70 feet deep and that depth is hampering search efforts.
Investigators do not suspect foul play.
Besas' parents told ABC11 Eyewitness News their son is good swimmer. He also is a recent UNC graduate and accomplished motorcycle racer.