I think it is possible to go up to the waterfalls with somebody who has a 4x4 the hubble hubble is expensive anyhow, some organize tour. We traveled with 2 kids 3 and 12 and that went relatively well but would have done more in organized tours than finding own transport. Mike adventures diveshop would be a good option but not sure he is open than, they where closed at sundays if I recall.
Sorry can't help you much, hope you have a nice trip |