Remarkable for the very large volumes of its rooms and its varied Concretions, it was destined for tourism and is now classified a Grand Site de France.

[2] On 19 August 1935, led to the Bertras sinkhole by the villagers, five speleologists descended into it: Joly, Latour, Abbé Glory, Petit and Chagnard.

Upon returning to the surface, Joly had three municipal councilors sign a report attesting to the authenticity of the exploration of the sinkhole “where, to our knowledge, they were the first to have descended”.

He had tourist development in mind, and the very evening of the meeting, he wrote a letter to Mayor Paul Delarque emphasizing the qualities of the cave, with capitals and emphatic quotation marks: ““A discovery like “BERTAS” is UNIQUE in the life of an underground explorer”, and flattering comparisons: “M.

De Joly was appointed operations director of Aven on December 17, 1938 On July 11, 1939, there was the inauguration in the presence of the Minister of Agriculture and several parliamentarians.

De Joly strives to make people talk about the cave, which is cited in a number of newspapers, put into poems, songs and "stories in the rose water ".

The 1960s also saw the crossing of the cat flap at the back of the North room, Orgnac II, III and IV were discovered in 1965 and 1966: the network was multiplied by five.

Unique in the history of speleological explorations, the authorities were mobilized with a visit to the new networks organized on 3 August 1965, two days after the discovery, for around forty people including the sub-prefect, the municipal council and the press, and another visit to the same networks on 12 September 1975 for the Secretary of State for Tourism and the Prefect of the Ardèche.

All this bustle around the cave has not harmed its tourist attendance, on the contrary: in 1971, Jean Trébuchon wrote that this increased after the discoveries of the years 1965-1966.

Then, the only one authorized to study the cave was Philippe Renault who, mandated by the town hall seeking to thwart Issirac's projects on Orgnac IV, conducted an expertise there on 13 and 14 June 1972.

Hence Yann Callot's thesis (1979) contains only three pages on Orgnac: there he admits his shortcomings regarding the cave, explaining that he was prohibited from entering the rooms outside the tourist part which “is not significant to the rest of the network”.