| Kirnitzsch | |
| Name Other: | Křinice, Kirnischt |
| Subdivision Type1: | Countries |
| Source1 Location: | in Šluknov Hook in the Czech Republic west of Studánka |
| Mouth Location: | in Bad Schandau into the Elbe |
| Basin Population: | 2266 (as at: 1999) in the Kirnitzsch valley |
| Basin Landmarks: | Small towns: Bad Schandau |
| Discharge1 Location: | at Kirnitzsch valley (above its mouth) gauge |
| Discharge1 Min: | Record low: (in 2005) Average low: |
| Discharge1 Max: | Average high: Record high: (in 1995) |
| Tributaries Right: | Zeidlerbach, Weißbach, Heidelbach |
| Tributaries Left: | Rotes Floß |
| Waterbodies: | Reservoirs: Obere Schleuse |
| Custom Label: | Navigable |
| Custom Data: | no |
The Kirnitzsch (German), in Bohemia also called the Kirnischt,[1] '''Křinice''', is a right tributary of the River Elbe, which passes through the Czech Republic and the German state of Saxony.
The Kirnitzsch, also called the Kirnscht or Kirnsch in the local dialect, rises in the Lusatian Highlands in Bohemia west of the village of Studánka (German Schönborn) and flows westwards through the town of Krásná Lípa (Schönlinde). Behind the village of (Khaa, part of Krásná Lípa) it wends its way along narrow ravines through the sandstone rocks of Bohemian Switzerland. The wild, romantic valley is also called the Khaatal (Kyjovske údoli) (Khaa valley).
On the site of the former village of Hinterdaubitz (), demolished after 1945, the border stream of Weißbach empties into the Kirnitzsch, which, from this point, forms the border between the Czech Republic and Saxony. Further downstream the Kirnitzsch is first impounded at the Obere Schleuse ("Upper Lock") so that boating can take place on the stream.
At the end of the Kirnitzsch Gorge (Kirnitzschklamm) used to stand the houses of the border village of (Hinterdittersbach) and the settlement of Křinice (Kirnscht). These places, too, no longer exist. From here the Kirnitzsch flows through Saxon Switzerland, where it is impounded again at the Niedere Schleuse ("Lower Lock"). Shortly thereafter the Kirnitzsch enters the narrow Kirnitzsch Valley (Kirnitzschtal). It flows through the valley for about to the Lichtenhain Waterfall. After another 8km (05miles) it discharges into the Elbe at Bad Schandau. Over its last few kilometres it is followed by the Kirnitzschtal tramway that runs parallel to the Kirnitzsch.