If you are planning to reach Alonnisos by boat from Volos, then prior to your trip you need to reserve and pay for tickets tickets for the roughly 3.5 hour boat trip on to Alonnisos. To book passage, visit Ferryscanner.com. The is fairly easy to navigate, just choose your ldeparture and arrival ports, the dates, and then follow the prompts. As of the summer of 2019, the old Hellenic Seaways (Flying Cats, Skiathos Express Ferry) no longer exists as it’s now part of Blue Star Ferries. When you book with Blue Star it’s best to stop by the office of the Blue Star Ferries’ representative in Volos (I’m pretty sure it’s called “Sporades Travel”) with your confirmation and they will print you actual tickets. They also may ask you for a passport for identification. When you have your ticket(s), if the boat is leaving shortly I recommend you promptly proceed to the boarding area which is across the street from the travel agency.
Please note that a company called Aegean Flying Dolphins also operates older boats called Flying Dolphins that are smaller, and somewhat less comfortable than the Flying Cats. They are however, a bit faster than the Cats, and the price of the tickets is somewhat less. Note that if you have any concerns about rocky seas you may want to limit yourself to only booking a berth on the Cat. I recommend using the Ferryscanner.com site to learn what other boat options exist.
Staying in Volos
If the arrival time in Volos is such that you are unable to connect with a boat to Alonnisos, please check the Category Archives (to your right and up) under “Hotel in Volos” for information regarding the properties I recommend.