There are many slums in Mumbai and across India and it was a moral dilemma for us whether to visit or not. We decided against it as we didn't agree with going on a guided tour viewing people living in the slums like "animals in a zoo". We then actually stumbled into the smaller Apollo Bandar Slum completely by accident, without even realising. This slum overlooks Sasson Docks and Gateway to India. It's surrounded, by several small open-air markets selling all kinds of fresh and live produce, and household goods. As far as I'm aware this isn't visited by guided tour groups like the Dharavi Slum is. This means it doesn't have a stream of tourists walking through the streets.