Walk to Red Beach which has a magnificient red volcanic cliff. The black beaches of Kamarri and Perissa are also a sight to see but remember that these beaches are where most tourists congregate. For quiet and more private beaches, go to Monolithos or Vlihada ( Take a sandwich or some snacks with you as finding food here is not that easy ). Also, black sand can be very hot so include some flip flops on your packing list.
Almost all tourists do this so expect a bit of a crowd.
and see the view the villagers wake up to everyday. This requires a lot of stamina (going up a hill, that is).
The Santorini Caldera undoubtedly is one of the natural wonders on planet earth. The volcanic explosion that occurred here more than 3500 years ago forever changed the topography of the Mediterranean coast.
It may be uncomfortable, but try it at least once just for the experience.
Ask the hotel manager for details or go to a tour agency
Visit museums and galleries