ZANTE FERRIES offers 20% discount for roundtrip tickets (at departure and at the return) for itineraries from 10/6 to 15/9 only if the tickets are issued from 8/5/17 to 31/5/17. Also, from 1/7/17 to 2/9/17 there is a 30% discount for the itineraries of ADAMANTIOS KORAIS every Friday and Saturday>/strong> from Santorini to Ios- Sikinos- Folegandros- Milos- Sifnos to Piraeus.