Not only does Mulu contain big, spectacular cave passages, but it has an awful lot of them too – 345km to be exact and all within the boundaries of the National Park. These passages need to be surveyed and quantified otherwise there is no evidence of their existence. Since the first expedition in 1978 all the caves have been surveyed and reported in published journals. However, keeping up with the rate of discovery has been quite a challenge for the 15 subsequent expeditions and the 20,000 individual survey legs that have been recorded. More so has been the challenge of changing priorities and technologies. Only in recent times have laptops and computer software been available to manage datasets and illustrate surveys. In this section there is information on the historical developments, the cave survey dataset, the drawn surveys and other technical issues.