Hey Sayali,
There is no need of swimming for scuba diving.
These are the places in India where you can go for Scuba :
1)Andman and Nicobar Islands
2)Goa
3)Lakshadweep
4)Pondicherry
5)Kovalam-Kerala
Hope this helps.
Swimming skills has got to do nothing with Scuba Diving and though there are few places in India to do Scuba; Andaman is the most worthy. Outside India, Thailand is amazing.