In the vast limestone formation which, under various names, extends through Carinthia, Carniola, Istria, Dalmatia, Albania, and Greece, the whole country is perforated like a sponge by an intricate system of subterranean water-courses. In the more elevated districts of the Morea there are many deep land-locked valleys or basins inclosed on all sides by mountains of cavernous limestone. When the torrents are swollen by the rains, they rush from the surrounding heights into these basins; but, instead of forming temporary lakes, as would be the case in most other countries, they are swallowed by chasms, which are sometimes situated in the middle of the plain, constituting the bottom of the closed basin, but more commonly at the foot of the surrounding escarpment of limestone. During the dry season, which in Greece alternates almost as distinctly as between the tropics with a period of rain, these chasms are the favourite retreats of wild animals.
Sometimes, in the limestone formation, the same stream repeatedly gushes forth from some cavernous recess, and then again disappears. The caves of Adelsberg, Planina, and Upper Laibach in Carniola are traversed by the same river, which, losing its name every time it plunges into a new subterranean channel, is called, first, the Poik, then the Unz, and finally the Laibach. In the same manner the Temenitz, an affluent of the Save, thrice disappears under the earth, and thrice emerges as a new-born river with another name.
As far as these subterranean streams have been explored, their course exhibits a wonderful variety of interesting underground scenery. Sometimes they form high cataracts, leaping over rocks so picturesquely grouped that, were they illumined by the sun, and of more easy access, they would be admired by numberless tourists; and not seldom they expand into dark and melancholy lakes. Sometimes they with difficulty force a passage through a chaos of rocks, and then again they flow gently in a deep and even channel, so as to be navigable to a considerable distance. Generally, not the least breath of air sweeps over their placid waters, but sometimes their surface is rippled by the wind pouring in through some unseen chasm.
Among the bold explorers who have launched forth their barques on unknown subterranean rivers, the late Adolph Schmidl, of Vienna, holds a conspicuous rank. In a canoe specially constructed for the purpose he trusted himself to the dark streams of Carniola, which rewarded his adventurous zeal with many a scene of incomparable beauty, where the water-spirits and the gnomes seemed to have rivalled each other in the work of decoration. To give an idea of the difficulties and of the enjoyments of these subterranean explorations, we will follow the intrepid naturalist on his voyages of discovery through the famous Cave of Planina, through which flows the Poik, a river which is at all times deep enough to carry a boat. The course of the navigation is stream-upwards, and consequently much safer than would otherwise have been the case; but in many places the rapidity of the current calls for great caution, and considerable strength is needed to overcome its violence; while at the same time great care must be taken to avoid striking against the rocks that lie hidden under the water. As far as the end of a magnificent dome, situated about 600 feet from its entrance, the cave can be traversed on foot; but here the sullen stream, completely filling its whole width, compels the explorer to trust to his canoe. When he has passed a portal about eight fathoms high and half as broad, with proportions as symmetrical as if it had been sculptured by the hand of man, the thundering roar of a distant cataract announces still grander scenes. The portal widens, and the astonished explorer suddenly emerges on a lake 250 feet long and 150 feet broad, beyond which the cave is seen to divide into two arms, giving passage to two streams, whose confluent waters form the lake. This broad sheet of water affords an imposing but melancholy sight. The walls of the cave rise everywhere abruptly out of the water, with the exception of one small landing-place opposite to the portal at the foot of a projecting rock or promontory. Here and there large masses of stalactite hang like petrified cascades from the rocks, which are generally naked and black. The vault is so high that the light of a few torches fails to pierce its gloom, which is rendered still more impressive by the roar of the waterfall in the left branch of the cavern.
As far as the lake, the cave is of comparatively easy access, and has been repeatedly visited, but the subterranean course of the two brooks beyond was first explored by Dr. Schmidl. In the left or western branch of the cave, into which he penetrated to a distance of more than a mile, his boat had to be unloaded no less than eleven times on account of the reefs that obstructed its passage, while the explorers, wading through the water, dragged it over the shallows. Once even, where the navigation was interrupted by large masses of rock, under which the tumultuous waters disappear with a dreadful roar, they were obliged to take the little shallop to pieces, and to reconstruct it on the opposite side of the mound. The navigable part of this western branch ends in a circular dome, the floor of which is entirely filled with a lake 180 feet long, and from 40 to 45 feet deep. On the western bank of this lake, a chasm opens at the top of a mound of rubbish, the only place where it is possible to land. A violent gust of wind descends from this chasm, which, sloping upwards, soon narrows to a small crevice, through which the current of air sets in.
To a lateral gallery, opening beyond the mouth of the chasm, Dr. Schmidl gave the name of ‘The Stalactital Paradise,’ on account of the uncommon beauty of the spar-crystals with which its walls were incrusted. It was the first time that the foot of man had ever penetrated into this charming laboratory of nature; no torch had ever soiled its brilliant decorations; no profane hand had ever damaged its gem-like tapestry. Here whole groups of stalagmitic cones, of all shapes and sizes, some like tiny icicles, others six feet high and as thick as a man’s waist, rose from the ground, while further on the brown wall formed a dark background, from which projected in bold relief the colossal statue of a sceptered king. Near the entrance stood a magnificent white figure, which fancy might have supposed to be a cherub with a flaming sword, menacing all those who should dare to injure the wonders which he guarded.
‘“The Stalactical Paradise” remained intact,’ says Dr. Schmidl.[[18]] ‘I begged my companions not to strike off the smallest piece of spar as a memorial of our visit, and they all joyfully consented. Our feet carefully avoided trampling down any of its delicate ornaments; we left it with no other memorial than our admiration of its beauty. The nymphs of the grot will no doubt have pardoned us for having intruded upon the sanctuary, where for countless centuries they had reigned in undisturbed solitude and silence.’
The eastern branch of the cave, through which the main stream flows, is much larger than the branch above described; it is also easily navigated, as it contains but two reefs and a small number of cliffs. On first ascending the stream, the continually increasing roar of waters announces a considerable waterfall. Enormous masses of stone, piled up by the falling in of the roof, have blocked up and narrowed the bed of the river to fifteen feet, and cause the stream to shoot down in a broad sheet ten feet high. The cataract, madly rushing over the jet-black rocks and casting up flakes of milk-white foam, is very beautiful, and, when brightly illuminated, must produce a truly magical effect.
Beyond the cataract the river flows for a short space in an invisible channel, as its waters are completely hidden under rocks. It was no easy task to carry the planks of the dismembered boat over these rugged blocks of stone, but after reconstructing it on the opposite side of the mound, and overcoming the minor obstacles of a couple of reefs, the river was found to flow in a deep channel between steep walls, and a free navigation opened to a distance of at least a league and a half.
‘No description,’ said Dr. Schmidl, ‘can do justice to the fascination of this subterranean voyage. In some parts the roof is adorned with coral-shaped draperies of snow-white stalactites, but generally the walls are mere black, naked stone. Here and there sources gurgle down their sides, and, along with the melancholy trickling of single drops of water from the vault, alone break the silence of the dark interminable cave. The breathless attention we bestowed on the guidance of our boat and on the wonders that surrounded us sealed our lips, and we glided silently along through the dark waters, that now, for the first time since they began to flow, reflected the glare of a torch.’