Everyone knows about the Mykonos and Santorinis of the world where Greek islands are concerned. However some of the more unknown gems throughout Greece are the ones with the most beauty, in my opinion.
Kythira Island is just a short hour boat ride from where I am from in Greece in Neapoli Lakonia but it is also accessible via Athens, Gytheio and Crete. There is also a national airport.
There is tons to see and do in Kythira including beautiful beaches, visits to monestaries and caves, hiking, and even a visit to Antikythira another quaint island. One of the biggest attractions would definitely be a trip to Xora, or the capital of the island.
At the hilltop of Kythira Xora you have a Venetian castle built in 1503 and within the walls are ruins of the Venetian buildings, 21 Byzantine and post byzantine churches and views of Kapsali and Filoti bay. On the outskirts are beautiful homes, plenty of souvenir shops and dining options. There is also an archeological musem for those more interested in a deep delve into the history. A common theme through this years destinations for Greece is just wandering the streets and getting lost. Be sure that everywhere you turn is the perfect opportunity for a photo-opp.