The Slănic (sometimes referred to as Slănic de Gura Ocniței or Slănicul de Jos to distinguish it from other rivers named Slănic) is a left tributary of the river Ialomița in Romania. It discharges into the Ialomița in Comișani. Its length is 30 km (19 mi) and its basin size is 82 km (32 sq mi).