Here is an article which gives some idea of the size of the passages to be navigated:

https://www.nytimes.com/interactive/2018/07/06/world/asia/thai-cave-rescue.html

There is considerable confusion about how far into the cave the group is located -statements vary between 2.5 miles and about 1.25 miles. I suspect some journalists are struggling with conversions from metric to English systems, since 2 kilometers is just about 1.25 miles....