Hello Arjit, To visit Andaman 7 days is enough & best time to visit is after mansoons in Andaman to May. Plan your trip when there are no rains in Andaman, rains in Andaman will definitely ruin all your plans. Find some places below in Andaman to visit & not in any particular order 1. Havelock Island ( swaraj sweep)
2. Elephant Beach
3. Sea adventure - Scuba diving
4. Baratang - Mangroves
5. Cellular jail
6. Mahatma Gandhi Marine national park
7. Corbin cove beach
8. Viper Island
9. Samudrika Naval Marine museum List goes on.... Have a wonderful trip..!