Visitors are to be charged €20 each to view what is thought to be the world's largest free-hanging stalactite in Pol an Ionain cave in Doolin, Co Clare.
The cave is due to open to the public in April and the admission price is due to the limited numbers allowed as part of the planning permission by An Bord Pleanála.
Helen and John Browne won a 15-year battle to develop the cave as a tourist attraction in the face of stiff opposition from An Taisce and the Pol an Ionain Action Group.
An Bord Pleanála stated that the Great Stal "is a significant part of Ireland's cultural heritage due to its scientific and aesthetic importance".
Until now, access to the cave has been restricted and Ms Browne said there is a limit of 55,000 visitors to the cave annually. She expects between 25,000 to 30,000 visitors in the first year.
She said that excavating of the passage that leads to the stal has been ongoing since last June and is nearly complete.
"It is a very difficult job. The rock is very hard and the rock has to be removed by hand as explosives can't be used in order that the stal is not disturbed. The monitoring of any vibrations and the temperature of the cave continues to ensure that there is no impact on the stal."
Ms Browne said the opening of the cave should help the local tourism industry. She said they will have invested €1 million in the project and it will in no way pose a threat to the Ailwee Caves, north of Ballyvaughan.
