No disrespect intended Andy but a female or anyone going to a waterfall on their own is not being sensible. That is crazy! A female going to a waterfall on her own here would be unthinkable. In PNG she would be lucky to get away with just losing her wallet and phone.
I used to go to the beach in Wewak on my own. A private beach on villagers land. I used to go there on my own and was the only expat there alone. The reason I could do this confidently is that I had an extremely well trained 60 kg Doberman with me. Anyone who came within 50m of me or my stuff received a warning "look" from Sheba. That was all that was needed and I never had any problems but without Sheba I wouldn't have dreamed of going to a remote spot on my own. Of course there are problems here, rape, murder, car jackings on a daily basis but all I'm saying is that if one is sensible the chances of these terrible situations occurring can be minimised or greatly reduced.