At the south end of Malham Tarn, water which is destined to become the infant River Aire sets off on its long (and complicated) journey to the North Sea. The journey is complicated because, just a few hundred yards from leaving the tarn, the river mysteriously vanishes through deep fissures in its limestone bed at a place called, quite appropriately "Water Sinks"..
For many years, it was believed that this river was the same as Malham Beck, reemerging further down the valley at the base of Malham Cove (i.e. the most obvious course: simply tracing the route of the dry valley which leads from Water Sinks down to the cove itself - and which way the water would have almost certainly flowed before finding the route underground).
However, this is in fact not the case, as flourescene dye tests have now proved that the river disappearing underground at Water Sinks does not actually reemerge until much further downstream, the point of debouchure being a place which is called Aire Head Springs south of Malham village. [Malham Beck, meanwhile, appears to originate at another location on Malham Moor, before also disappearing underground to resurface at the famous rising beneath Malham Cove !]
It is clear that, whatever routes are actually taken by these streams underground, an extensive network of cave systems still lies waiting to be discovered, despite the valiant efforts of cave divers to penetrate the depths of the submerged boulder crawl which lies beneath Malham Cove.