A Kerry spate river draining the mountains south-east of Killarney into Lough Leane — part of the Laune/Killarney system. Salmon, sea trout and brown trout run on a flood; old red sandstone water that needs rain to fish. Atlantic salmon and sea trout are managed under IFI's Wild Salmon & Sea Trout Tagging Scheme — many rivers are catch-and-release and harvest is allowed only where a confirmed surplus exists, so check the river's current status before fishing.
EPA freshwater monitoring on the River Flesk confirms mayflies, stoneflies, caddis, aquatic diptera and freshwater crustaceans are present across its monitored segments. The records establish food presence rather than adult emergence timing or a dependable rise.
- Old red sandstone

