I had not been able to cover Auroville beach because of scuba diving training. Scuba diving in pondicherry is one of the best & there are many PADI accredited institutes which train you for scuba diving. We were a group of 3 friends and got a deal of 6500 per person , the larger your group, the better discount you can expect to get. Also , do remember to keep half a day for scuba diving because the whole process involves taking all the groups to middle of the sea and then the number of people going in depends on the number of divers available ( 1:1 diver & person ratio). We got really tired after coming back from the dive however it's extremely picturesque experience to be inside the ocean.
Start your day with surfing. And if you are still in it go to auroville