There are every day routes from the port of Piraeus to Sikino. The line Paros - Naxos - Ios - Sikinos - Folegandros - Thira - Anafi connects the island with Athens and the rest of Cyclades islands.
During summer period Sikinos is also connected with Kithno, Syro, Serifo and Milo.
For more information:
PORT AUTHORITIES OF PIRAEUS 210 4226000
PORT AUTHORITIES OF SIKINOS 22860 51222