For those who have the need to relax and experience a tranquil environment out of the crowds and the noise, i highly recommend you to visit Santorini during winter!
Not much to do regarding entertainment but you can enjoy the real beauty of the island without interactions! The sky colors, the sunset and wild beauty of the winter in Santorini is really one of a kind!
I believe that Santorini is ideal in winter for those who look for the alternative things. For example, its the best periode to go hiking, the hiking routes are empty so you can enjoy a great hiking (interesting hiking routes are those of Ancient Thira from Peirssa, Caldera Megalochori, Fira to Oia and Pyrgos to Prophet Elias monastery. Visit the most interesting archeological places, such as the archeological site of Akrotiri dating back the 4500 BC, which is an amazing experience (do not forget to have a tour guide with you), explore the archeological site of Antient Thira 900 BC also of great interest. Visit the archeological museum in Fira as well as the Marine Museum in Oia. Another interesting visit is at the local wineries and the wine museum. Taste the unique wines of Santorini which i find them really special, look for the Art gallery open in Exo Gonia. If you seek having a boat tour around the volcano, there are some boat tour agencies still open during winter which offer daily tours at the volcano, if the weather is good.
Other things to do…
Visit my favorite traditional port of Vlychada, wonder around, sit and admire the beauty of the sea, go at the port to eat at the Fisherman’ place, Mrs Roula and her family (all fishermen), they cook daily fresh fish and so many other delicious things. Its very authentic and traditional, also prices are very good!
A nice idea is also to go to cinema, have a nice dinner in Fira (recommended places such as The Bone, Kokkalo, The Garden at Pelican hotel) or in Karterados village (Kyra Niki Greek cuisine with live music on Saturdays, Tobasco Italian restaurant) and at Exo Gonia (Aroma Avlis)..