Water patrol and Boone County response crews have been searching for him since just after 2 p.m. near Cooper's Landing, where he was last seen swimming with two others before disappearing beneath the surface.
Crews are calling the search a recovery, not a rescue, effort. They're using sonar and reaching devices to try and find the teen's body in the water, where the depth ranges anywhere from 18 to 42 feet.
* Officials originally reported that the teenager was 15. The story has been updated to reflect the latest information.