If you want to experience a classic beach destination while in India, I would suggest travelling across to Goa.
Expect some stunning beaches and resorts and, although it’s touristy, it would tick most boxes of what you would be looking for from a beach break.
Alternatively, laid-back Varkala is located beside some stunning cliffs, in Kerala in India’s south-west. However, it is quite a journey from Calcutta, so either build it into a bigger, longer trip on the subcontinent, or fly to Mumbai and take the train to Kochi to start a tour, which includes a visit to the Periya Tiger Reserve.
Best Beaches in Goa
The main attraction of Goa is the beaches which are among some of the best in the country.
Palolem Beach
I would recommend checking out Palolem Beach – it is less touristy that some of the north Goa ones (even over Christmas), although it is a bit busier than! That said most of the hawkers on the other beaches will be happy to leave you to your own devices if you let them know you were not interested (a smile always helps too!).
Morjim
Where the turtles hatch and also a nice break for a night.
Arambol Beach
Arambol Beach has lots of character.
Places to Visit Near Goa
If you can, go further south to Gokana rather than Goa. Gokana it is much less touristy and there you will find Om beach, and Paradise beach.
Alternatively fly (or take a five day boat trip) down to the Andaman Islands after Calcutta. Its still India and the beaches here are meant to be the best (just so long as it fits into the budget).
Goa Travel Tips
My advice for Goa is not to fly into Delhi – way more scamming there than the south. I flew into Mumbai (Bombay) and found the people there to be mostly hospitable and genuine. Where else could you go where the bus driver diverts to the train station just for you – or where people on the bus (or train) help you on with your backpack?!
Some more recommendations would be to book at the non tourist offices for trains – and to do second class sleeper. This didn’t have aircon like first class but did have fans. You could get good priced flights to the Maldives from the south also – although you would need to co-ordinate with train possibly?
Enjoy your trip to Goa!