Turloughs are transient lakes which occur in shallow depressions where the water-table, or upper level of groundwater, lies close to the land surface. They are usually dry in summer and in dry weather when the water-table is lower, whereas they may be flooded in winter and in wet weather when the water-table has risen.

Turloughs can appear and disappear over a few hours or days. Turloughs occur in the limestone areas of Clare and east Connacht . Examples are to be found in the Carran depression of the Burren, and on the lowland around Gort in south Galway .

The word turlough is derived from tuar loch, dry lake. A distinctive flora is associated with turloughs.