The deep caves
On the Kanin plateau, more than a dozen caves descend over a kilometre. One holds the deepest single shaft known on Earth.
A plateau full of holes
For reading, not for visiting.
The show caves of the south are horizontal: rivers made them. The caves of the Julian Alps are vertical. On the high plateaus of Kanin and Rombon above Bovec, snowmelt and rain drop almost straight down through 2,000 metres of limestone to springs in the Soča valley.
The surface is a bare pavement of rock scored by runnels and split by fissures. Many of those fissures are the tops of shafts. More than a dozen caves in this small area are over a kilometre deep, one of the densest concentrations of deep caves in the world.
None of this is open to visitors. These are expedition caves, explored over decades by Slovenian, Italian, British and other clubs. They are described here because they are part of what makes this small country remarkable underground.
Six hundred metres of nothing
In 1996 a joint Slovenian and Italian team descended a shaft on the Kanin plateau that simply kept going. Vrtoglavica, the name means vertigo, contains a single uninterrupted vertical drop of 603 metres, the deepest known pitch in any cave on Earth.
A stone dropped from the top takes more than ten seconds to land. A waterfall that enters partway down is among the highest underground falls known.
More than 1,000 metres down
Reaching the bottom of a kilometre-deep cave takes days. Teams rig hundreds of metres of rope, carry everything through tight, wet meanders, and sleep in underground camps. The reward at the bottom is usually a sump: a flooded passage that stops everyone except divers.
In Renejevo brezno the terminal sump lies beside a beach of pale sand that cavers named Copacabana.
The longest cave in the country
Tolminski Migovec is a grassy plateau above Tolmin. Since 1974 students from Imperial College London have returned almost every summer to explore it together with cavers from Tolmin. Separate caves have been linked one by one into a single system now more than 40 kilometres long, which overtook Postojna as Slovenia's longest.
It is a reminder that exploration here is unfinished. New passage is surveyed every year.
Slovenia's deepest and longest
Depths and lengths grow as exploration continues; figures are rounded.
| Cave | Massif | Depth | Notable for |
|---|---|---|---|
| Čehi 2 | Kanin massif | about 1,500 m | Deepest cave in Slovenia |
| Črnelsko brezno | Kanin massif (Rombon) | about 1,390 m | Several entrances linked in one system |
| Renejevo brezno | Kanin massif | about 1,320 m | Reached a sump named Copacabana |
| Mala Boka – BC4 | Kanin massif | about 1,320 m | A through-trip from plateau to valley spring |
| Vandima | Kanin massif (Rombon) | about 1,180 m | Among the classic deep systems of Rombon |
| Sistem Migovec | Tolminski Migovec | about 970 m | Longest cave in Slovenia, over 40 km |
| Vrtoglavica | Kanin massif | about 640 m | 603 m single pitch, deepest known in the world |
Vertical Slovenia
In pictures
These caves are not tourist sites. They require single-rope technique, cold-water equipment and experienced teams. If they appeal to you, the way in is through a caving club. See Caving safely.
See the karst from above
A cable car from Bovec climbs to the edge of the Kanin plateau, where the limestone pavement can be seen without ropes.