Loughareema, also known as the Vanishing Lake, is located a few miles from the seaside town of Ballycastle in Ireland. The lake sits on a leaky chalk-bed with a 'plug hole' that often becomes jammed with peat causing the Loughareema depression to fill, especially during heavy rain. When the plug clears, the lake drains rapidly underground. A passerby who is not aware of the lake and its disappearing act would never even know it existed in the first place.
Interestingly, the road to Ballycastle runs right through the lake, though the modern road sits high enough to avoid flooding, unlike the original. It is quite possible that even the road engineers who built the road were fooled by the lake's trickery. In former days the route was frequently under water, sometimes for weeks on end, making crossing treacherous.