next to the site where MV Smart sank, I have spotted a row of underwater sources emitting some "other stuff" than simple disposed sewage. curious phenomena can be seen by various imagery dates from 2005 up to 2015.
double click on each placemark (only visible) in kmz folder will bring you to proper imagery dates by which emitting is visible. underwater source.kmz (1.46 KB)
an example by a maximum level of emission:
what it is? -can be pollutant? -sewage? -or some harmless sediment departure process from the heavily shipped bay-waters? -have never seen such before... ...amongst the many other things...(:
*** have also edited OP title and let it with "?" until something-for-sure about the one at Richards Bay.
instant edit: Two more sources (PDF.file#1 from a lecture on lth.se // PDF.file#2 on springer.com) convinced me, question mark can be omitted,
and PressReader.com article has put it to an end with further sites along South Africa coast, Richards Bay included.
This latter source gives also measures and details of the waste water spilled in the ocean (domestic/oil-industry/chemical/etc.): Only "the city of Cape Town marine outfalls can discharge up to 55 million litres of waste water a day."