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.

Between Ostrov and Constanta, the road provides a vital link between southwestern Dobrudja and the rest of the country.

DN3 connects with the Bulgarian road network through a border crossing facility at Ostrov – Silistra (Bulgaria), immediately after the ferry landing.

Thus, if counting the Călărași-Ostrov ferry as part of the DN3 road, it can be said that one of the main remaining roles of DN3 is providing a connection between Călărași and Silistra.

Note that as of 2009, there is also a direct, newly built Călărași – Silistra ferry, but is far slower (takes almost 2 hours to cross the 8 km distance) and far more infrequent.