The Free Lance-Star reports that the 15-year-old disappeared on Monday afternoon in the area of the Historic Port of Falmouth.
A search was called off after darkness set in Monday night and was scheduled to resume on Tuesday.
Stafford Sheriff’s Maj. Shawn Kimmitz said that the teenager entered the river, briefly surfaced in the water, then went under.
The incident is the third emergency on the river in eight days. The Rappahannock is always considered to be dangerous.
But significant rainfall has swollen the river with swift currents and debris.
Officials say that more than 80 people have drowned in the Rappahannock since 1985.