The only and best sites are pretty far from Buenos Aires city. (1500/1600km)
They are:
1 city of Puerto Madryn, in december you can see right whales and his puppets from the coastal street. Jumping off and mating. Its forbiden to dive with them, but if anyone appears moving around while youre alredy diving....its ok. Lots of sea lions. Some wrecks, no pentration allowed.
2 Puerto Piramides, the same in a small summer village. Near P Madryn (200km) and inside Peninsula Valdez. From the sandy beach the boats are carried with wales watchers, tourists from many countries. Dives Shops 3 or 4, in the main street. Best sites: Isla Pardelas and Bahia Pardelas . Semi cold
3 Las Grutas city, in Rio Negro province. Only one operator "Cota Cero" with a pretty good -and cheap for you- service. The water temperature here is no so cold than Madryn/Piramides because the low pendient of the bottom, and the great amplitude of the tides. Recently a ship has been sinked, for diving.
4 Mountain lakes: Nahuel Huapi in Bariloche, Rio negro province. 1600km far from Buenos Aires. On the same great lake, the village of Angostura has 1 or 2 dive operators. Cold waters.
In all these points you´ll find english speakers, owners/DM , no big deal.
Hasta pronto!
Saludos
Kalito