The Nusa Dua area on the southern tip of Bali does have a few dive sites but they are nowhere near the best that Bali has to offer and the only thing to recommend them is that they are close to the resort areas of Kuta Beach and Sanur.
For divers who are short of time they offer a chance to get wet and listen to bubbles. Marine life is ok but the coral health is pretty poor with lots of dead coral rubble.
The reefs are suitable for beginner divers and for training dives. Currents are usually mild.
Fringing reefs around Serangan Island slope down to about 20m and can be interesting. Unusual macro critters can always be found, as on all Bali dive sites. Divers can find lionfish and scorpionfish and blue spotted stingrays may be seen in the sand.
Visibility is worse than in other parts of Bali due to boat traffic in the area from Benoa harbour.