Cango One- unexpected dead end

The mystery of the unexpected dead end of Cango One was cleared up in 1956, when the Spelaeological Society surveyed the caves. They noted that when the atmospheric pressure outside dropped, air flowed into the caves and when atmospheric pressure mounted, air flowed into the caves. This proved that there was a continuation of the cave sequence. In 1972, three professional cave guides broke through to a breathtaking fairyland, a 270-metre extension of the sequence, Congo Two. In 1975, another extension of about 1600 metres, was discovered and named Congo Three.