My experience is that Sodwana is OK, (the beach is like a shopping mall car park on a saturday morning, unless they have banned vehicles now). The dive sites are crowded, and the boats take every one to 2 mile reef all day (quick turnaround), but try and get to 5, 7 and 9 mile reefs, if you go there. Looking at my logbook, water temp varies between 21 and 25 degrees C, visibility 10 to 20 meters, sometime more. What you see is colourful coral, and subtropical fish, eals turtles cray's, octopus, stone, scorpion, lion, various angel fish, wrasse, dolphins etc etc. There is better diving, IMHO, is just a little further up the coast in Southern Mocambique, Ponto do Ouro, Ponto de Malongane, Coral Gardens (at Malongane) rates as one of my best dives ever (acres of uninterrupted, pristine coral, at 12 meters, with attendant subtropical fish, and on that dive a whale shark). By now the resorts probably extend a few bays further north. I think you should split the trip into a Safari part where you are based in or near the game reserve ( part of the fun is the 6am game drive), and then a diving trip where you are based at the beach. My info is about 10 years old so hopefully a local will advise you on current conditions. A long way further south is Aliwal Shoal, famous for dives with ragged tooth sharks (I recall a memorable night dive in Raggy Cave!), and a wreck at around 30 meters ""The Produce"".
Good luck with your plans, whatever you decide it will be great.
