Jizera Mountains, or Izera Mountains, are part of the Western Sudetes on the border between the Czech Republic and Poland. The range got its name from the Jizera River, which rises at the southern base of the Smrk massif. The beech forests within the Jizera Mountains were added to the UNESCO World Heritage Site known as Ancient and Primeval Beech Forests of the Carpathians and Other Regions of Europe, because of their outstanding preservation and testimony to the ecological history of Europe since the Last Glacial Period.

The Jizera is a river in the Czech Republic and for a brief stretch in Poland. It is a right tributary of the Elbe River. It flows through the Liberec and Central Bohemian regions. It is 167.0 km (103.8 mi) long, which makes it the 10th longest river in the Czech Republic.