Hranická propast

Hranicka Pothole - Weißkirchener Abgrund

Useful Information

Location: 4 km east of Hranice.
Open: no restrictions.
Fee: free.
Classification: KarstTiankeng
Light: n/a
Dimension: D=-473.5 m (above water -69.5 m, under water -404 m)
Guided tours: n/a
Photography: allowed
Accessibility: wooden walkway is wheelchair accessible
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


25-APR-1902 36 m depth of water measured with plummet by J. V. Sindel.
1960s first exploration attempts by draining the water failed.
1961 B. Kopecý dives 6 m deep.
1963 M. Kosteča dives 12.6 m deep.
18-AUG-1963 J. Pogoda dives 42 m deep.
09-AUG-1964 S. Huvar and V. Sráček dive 60 m deep and discover the entrance to the lift.
13-MAR-1966 V. Kocián and I. Gregor dive 82 m deep.
01-SEP-1968 V. Brenza and S. Hany dive 88 m deep.
02-MAY-1981 L. Bentýsek and F. Tarvěnec dive 110 m deep with a newly developed breathing mixture.
20-APR-1985 M. Cernik dives 100 m deep.
24-APR-1992 M. Pauwels from the Netherlands dives 134 m deep.
25-JUL-1993 M. Pauwels dives 155 m deep.
26-JUL-1998 D. Skoumal and M. Hasa dive 130 m deep.
23-NOV-2005 P. Riha dives 170 m deep.
Jiří Pogoda dives m deep.
1995 first attempt with a dive robot.
2000 dive robot reaches floor at 181 m.
2012 after years of surveying a second shaft leading further down was discovered.
27-SEP-2016 exploration with a diving robbot to a depth of 404 m below the surface.


The Hranicka Propast is the deepest single shaft in the Czech Republic and it is located in the Devonian limestone karst on the plateau above the eastern bank of the river Recva, opposite the health resorts of Teplice and Becvou, about 4 km south of Hranice.

There is a thermomineral lake at a depth of 69 m with a temperature of 12-15 °C. The pothole is believed to have been formed by the corrosion of the limestone by high yielding rich CO2 thermomineral springs ascending from a great depth. Only in the final phase did the roof collapse and giving rise to an open pothole.

Text by Tony Oldham (2002). With kind permission.

The Hranická propast (Hranicka Pothole) is located south of Hranice on road 35 (E442), near the train station Teplice nad Bečvou, opposite of the Aragonite Caves of Zbrasov. Park your car at the train station (fee) and walk through the train station, there is a marked trail on the other side up the hillside. The abyss is developed with a platform and a explanatory table. Because of the dangerous carbon dioxide gas, do not leave the trail!

This is a rather extraordinary karst object, as it is located at the hypogene karst around the Zbrasov Aragonite Caves. In this area a volcanic influence, most likely a magma intrusion below - probably even a magma chamber - heats the rock and the ground water and produces various gases, mainly carbon dioxide. The result is dissolution of limestone by the warm water which then reaches the surface as mineral rich thermal water. This cave formation process is becoming more attention in the last 20 years and there a numerous publications in this field, as a result this abyss has become an interesting object for speleological and scientific research.

The pothole is known for a long time, in Austro-Hungarian times it was called Weißkirchener Abgrund. Nevertheless, except for measuring the depth of the pothole to the water level there was no exploration possible. Early explorer even had difficulties to reach the water, because the carbon dioxide from the water is heavier than air and fills the pothole. Carbon dioxide is not poisonous, but as there is only cabon dioxide and no oxigen there is always the danger of suffocating. As a result the exploration was quite slow. Until today with new technology, gas mixtures and more, divers have reached a depth of 181 m, but they have only a few minutes at this depth, and then an ascend with decompression of 16 hours. This is quite costly in time, logistics and health of the diver.

As a result the Polish and Czech cavers around Pavel Říha decided to use dive robot for further exploration. One of the problems is to find the second drop at the bottom of the first drop, another the length of the glass fibre cable which is necessary for remote controll. They worked together with the manufacturer of the GRALmarine underwater equipment and they built a cave diving robot oprimized for this cave. The current success is they reached a depth of 404 m blow the surface. Further depths are likely, as soon as a longer landline is available. Unfortunately it is quite expensive, and the explorers, like most cavers on Earth, are financing it with their personal money.

The success of the 2016 exploration made this the deepest waterfilled cave on earth.