The dive sites are all marine sanctuaries of different sizes, all can be done by shore entry. It is amazing how this protected areas aer "working" as you will find outside the areas not much more than sand and as soon you dive inside you are in an aquarium.
the distance between Ducomi and Maajong Tubig is roughly 15 KM
A few more info about the Dumaguete area
here and
here
cheers
Rhoody