The Pregolya or Pregola (Russian: Прего́ля; German: Pregel; Lithuanian: Prieglius; Polish: Pregoła) is a river in the Russian Kaliningrad Oblast exclave.
It starts as a confluence of the Instruch and the Angrapa and drains into the Baltic Sea through Vistula Lagoon. Its length under the name of Pregolya is 123 km, 292 km including the Angrapa. The basin has an area of 15,500 km². The average flow is 90 m³/s.
Euler's Seven Bridges of Königsberg problem was based on the river's bridges in Königsberg, now Kaliningrad.
The ancient name by Ptolemy of the Pregolya River is Chronos.
Cities and towns
Coordinates: 54°41′N 20°23′E / 54.683°N 20.383°E