Loughareema in northeastern Northern Ireland is a small lake with no visible runoff that disappears periodically but unpredictably. The phenomenon is considered unique to Europe. This idiosyncratic lake is located on the coastal road near Ballycastle. The reason for the unusual phenomenon is that the lake is on a "leaky" chalk bed. If the drain holes are clogged with peat, the water can not run underground and collects again to a lake.
This happens in heavy rains, as they are not uncommon in Ireland, very quickly - and just as suddenly the lake disappears as soon as one of the described peat plug is no longer tight.