About the road around the dam. The one I am talking about is shown on T4A and north of the dam and which was cut off by the dam, but may be passable when the dam is very low. The road eventually goes to Prince Albert,joins and has turnoffs to other gravel roads along the way, many shown as private. Mr Foxy (Fox) who runs the cottages reckons it is not usable and strikes me that he can be a difficult bliksem.
Nothing is shown going into Die Hel but on our visit in Sept 2016 we did go back up Boschluiskloof Pass, off the road and down Die Leer into Die Hel (on mountain bikes; well carrying them) but this does need permission from land owners at the bottom and top plus some payments.
We had a serious adventure racer with us and she said they had walked, climbed and swam up the Gamka River from Die Hel and to the dam. A very tough lady though.
Not my neck of the woods sadly - I am a KZN banana muncher usually.