The Griffeen River is a tributary of the River Liffey flowing through County Dublin in Leinster, Ireland. As part of the greater Liffey catchment system, the Griffeen winds through a largely urbanized landscape before joining the main Liffey channel. It is a relatively modest stream in terms of size, yet it supports a surprisingly diverse fish community including wild brown trout, northern pike, European perch, and common roach. The river has been the subject of ongoing fisheries monitoring by Inland Fisheries Ireland as part of the EU Water Framework Directive biological assessment programme, reflecting its ecological significance within the Liffey system. Water quality has historically been a noted pressure on the Griffeen sub-catchment, and it remains one of the areas of concern within the broader Liffey system, though some improvements in ecological status have been recorded in recent years.