Sorry Shy, just caught your response. The best places for snorkeling in India are in the far South: the union territory of Lakshadweep and the group of five hundred and seventy two Andaman and Nicobar islands in particular come to mind. In the latter, the Mahatma Gandhi Marine National Park in Port Blair and the North, Middle and South Button Island Parks near Long Island are your destinations of choice. I'd also recommend the Dandeli Wildlife Sanctuary in Karnataka- a tropical paradise with all sorts of marine and terrestrial wildlife and some fabulous snorkeling. Further up north, you could also go snorkeling or scuba diving in the Bay of Bengal- although that is usually crowded with large fishing trawlers and oil & gas exploration ships.