If you are tempted to row on underground lakes, the Križna jama cave is the right place for you. It is world-famous for its underground lakes behind sinter barriers and sites of cave bear bones. The cave drains away water from the southern side of the Bloke plateau towards the eastern edge of the Cerknica plain.
The entrance part of the cave is known by its huge halls. The other passages are in some places cut off by sinter formations or rocks, limestone pools and smaller stalagmites and stalactites. Soon after a few hundred meters, the natural light disappears and the visitors continue their exploration with hand lamps. They are about to see remarkable things – bones of cave bears astonish with their size and number. The tour continues through the passage which drains off water from the first lake. The short, one-hour tour includes a boat ride on the first lake and return to the entrance along the same path.
If you opt for the longer tour, suitable for smaller groups, you will continue your way over the rocks from the first to the second lake. In the middle of the lake, the ceiling lowers and makes the entrance to the typical water passage difficult, which also marks the beginning of an unforgettable journey. Water streams over sinter barriers from one lake to another. Barriers, which are still rising, are formed by calcareous sinter, which is deposited from two streams. Water covers the stalagmites and columns, which gives the impression they are springing out of water (Beneški pristan – Port of Venice, Piratska ladja – Pirate's Ship, Orgle – Church Organ, Ris – Lynx). The lakes are up to 6 metres deep. At the beginning of the water passage, the lakes are short and then get longer towards the end. The tour ends at Kalvarija (Calvary), a hall rich with stalagmites and stalactites, where the cave divides into the northern part called Blata (Mud) and north-eastern part called Pisani Rov (Coloured Passage). The same way takes you back to the entrance.