Hi Eckart,
Let me know what your plans are and we can try make a plan....Knysna isnt good for shore dives, unless you want to walk urself into a Coma!. The best is Coney Glen but You need a really really flat sea to dive there, which can produce Cracker and a few other Rats and Tails, sometimes you'll get the Odd Leervis around there. This time of year the diving down here is really Crappy with the sea being cold and dirty most of the time.
As far as I know, Gerrickes is about the best for Shore dive.....
Let me know, Shot!