Ochtinská Aragonite Cave

Most show caves are made of calcite, dripping into the familiar stalactites and stalagmites. Ochtinská is different: here the mineral is aragonite, which crystallises into fine white needles, spirals and clustered sprays that coat the walls and ceilings like frost, coral or bunches of tiny flowers, and only a small number of caves anywhere display this on such a scale and are open to the public. Discovered by chance during mining work in the 1950s, it forms part of the World Heritage listing covering the caves of the Slovak and Aggtelek karst shared with Hungary. The visitor route is short, a few hundred metres, and lit to show the crystal formations, including a chamber known as the Milky Way where the ceiling glitters. Numbers on each tour are limited and humidity is carefully controlled, because the crystals are extremely fragile.

What you actually see

• The aragonite clusters - white needle and spiral crystals coating the walls.
• The Milky Way chamber - the glittering ceiling that gives the section its name.
• The Onion Hall - the rounded formations in the cave's largest space.
• The Slovak Karst - the wider limestone country and its other show caves.

When to go

April to October is the open season, with the cave closed through much of the winter; tours run at set times with limited numbers, so arriving early or checking times avoids a wait. It is around nine degrees inside year-round, so bring a layer whatever the weather outside.

Honest expectations

The tour is short, a few hundred metres and under an hour, so it is a stop rather than an outing, and it is best combined with the other caves and castles of the Slovak Karst. Photography is restricted or banned to protect the crystals. The cave closes for a long winter season. It is well off the main routes and needs a car.

Nearby

Domica and Gombasek caves are elsewhere in the karst; Rožňava and Betliar manor are close.