Ferries to Sporades from Agio Konstantinos
The pretty work-a-day village of Agios Konstantinos, on the main Athens–Thessaloniki route, is one of the three mainland ports (along with Volos and Thessaloniki) that serve the islands of Skiathos, Skopelos and Alonnisos, which make up the northern Sporades.
Hellenic Seaways operates the crossings to Skiathos (per person/car €30/69, three hours), Skopelos (per person/car €38/82, four hours) and Alonnisos (per person/car €36/78, five hours). In summer (June, July and August), smaller passenger boats called Flying Cats also ferry foot passengers to Skiathos (€41, two hours); Skopelos (€54, three hours) and Alonnisos (€54, 3½ hours). Both Flying Cats and car ferries operate from September to May, but with less frequency. See www.ferries.gr/greek-islands-ferry/ferry_agios_konstantinos.htm.
Ferries to Ionian Islands from Astakos
The only reason to head to Astakos (Αστακός) is for its convenience as a stepping stone for access to the Ionian Islands, via the daily ferry (the Ionio Pelagos) to/from the port of Sami on Kefallonia (per person/car €11/45, three hours), and Pisa Aetos on Ithiki (per person/car €9.20/36, two hours) in summer. For both crossings, there are one or two ferries daily, but check ahead with Ionian P. Lines as days and hours vary seasonally. In Astakos, a few cafes and tavernas line the small waterfront so you can get your fill while waiting.
From the KTEL bus station in Agios Konstantinos, 200m south of the ferry landing, there are buses to Athens (€17.70, 2½ hours, eight to nine daily) and Lamia (€5.60, 50 minutes, 12 daily). For Patra and Thessaloniki, you must change at Lamia.