DN3 (Romanian: Drumul Național 3) is a national road in Romania, originally linking Bucharest and Constanța via Călărași, but no longer serving this purpose for more than four decades. The road is not complete, in the sense of having a gap across the Danube between Călărași and Ostrov. The gap is covered by ferry-boats operated by two private companies every 30–35 minutes during the day and every 45–90 minutes during the night.