It might be argued that the largest single cave in the world is one whose overall volume is greater than any other cave. A number of international cavers have suggested that the Clearwater System would fit this position and consequently the National Park has used this claim in some of its publicity. Certainly it is a very long cave and one with a large average passage diameter and so should be a contender.
Currently there is no standardised method to measure cave volumes so these claims are subjective. However, there is a methodology developed by the Mulu Caves Project using standard survey data which supports this view. The method can be applied to all the big caves in the world in order to derive comparable volumes.
Using the cross sectional area at each survey station the volume of the Clearwater System can be calculated at 38 million cubic metres and therefore the average passage diameter is 16m along the entire 197km length.
This is likely to be significantly greater than any of the other longest caves of the world. Only the mighty Mammoth Cave System could perhaps exceed this volume and diameter, by virtue of its superior length. This would require an average passage diameter in excess of 8m and due to the large number of small passages in the system this would seem highly unlikely.
Therefore it is easy to conclude that of the world’s long caves Clearwater has the greatest volume.