There are a lot of ways to come to Kythira. Plane from the international Airport of Athens or boat from Piraeus.Also roadly up to Gythion and Neapoli Lakonia and from there again by boat. If you come from Crete you will find the boat in Kasteli of Kissamos (district of Chania).
You will find more information in the travel agencies, where you will buy your tickets. And don’t forget always in time, because the demand is big. Now if you come with your ship look the information in the category Marina .