The Piaśnica (German: Piasnitz) is a nearly 30 km long coastal river in the north Poland in the voivodeship Pomerania. It is very popular with canoeists and anglers.
Run
The Piaśnica rises on the northern edge of the Pomeranian Lake District (Kashubian Switzerland) between Wejherowo and puck and flows northwest through the Pomeranian lake and arts landscape towards Baltic Sea. Just before it converges in Debki at the Solviny Coast it flows through the coastal lake Zarnowitz Lake.