Stumbled across this rather unusual and rather beautiful water filled shakehole on the magnificent Brecon Beacons not far from Llangynidr.
A shakehole is a depression in the limestone landscape. In some limestone areas there is a covering of boulder clay about two or three metres thick. Shakeholes are formed where surface water washes the boulder clay down into cracks or fissures in the limestone under the boulder clay. Normally the shakeholes are just mysterious deep grass covered holes.