If you are a certified diver, I would suggest you Dixon’s Pinnacle on Havlock Island. It is the prettiest dive site in Andamans. If you are new to diving, I have attached a helpful link for you :) Happy Diving !!
If you are a pro diver, I would suggest Cinque Island. There are two dive sites there called North Point and South Reef. It's famous for Shark sightings (black tip reef sharks mostly). It also has good visibility. If you are looking for a night dive then this place might not be the perfect one as night dives are seldom permitted.
Hey Samiendra ....
Places for Scuba Diving in Andaman
1. In and Around Havelock Island
2. Experience night diving at Lighthouse
3. Aquarium – Bliss for Amateurs
4. Enjoy the scuba diving with Dugongs – One of the recommended places for scuba diving in Andaman
5. Say Hello to Sea Turtles at Barracuda City