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.