Chios has daily connections with Piraeus on the mainland(Hellenic Seaways, Nel Lines). The journey on the ferry takes approximately between 6 and 8 hours depending on the boat. There is also a regular connection with the island of Lesbos (or Lesvos), sometimes several ferries a day. This trip takes about 2 to 3 hours, again depending on the ferry and the route. The ferries to the south call on islands such as Ikaria, Fourni, Samos, Kos and Rhodes.
To the north you can go to Kavala (mainland - Saos Ferries) and Lemnos, and there are ferries to the smaller islands such as Oinouses and Psara. For exact times and routes look at the various ferry companies on the internet, or if you have booked a hotel on the island, you can also ask the hotel. The owner often knows better. Tickets for some ferries can be booked online in advance.
For schedules of the ferries to and from Chios and to order a ticket - click here.