What are the options for getting to Alonissos island from Skiathos in mid June? It seems there are ferries, but they only depart in the morning, however I will be arriving to the airport in the early afternoon.
In the summer there are up to 3 ferries per day on the Skiathos - Alonissos route, while in the winter there are at least 6 weekly crossings. The earliest ferry departure is around 10:30 from the port of Skiathos and the latest can be from 16:00 to 21.00 depending on the season and the day of the week.
Further, https://www.ferries.gr/en/ferry-companies/aegean-flying-dolphins/route/volos-skopelos-alonissos/ lists the Aegean Flying Dolphins leaving Skiathos on 15:40 arriving Alonissos a bit more than an hour later. It seems it is the opposite direction which leaves in the early morning but according to the above during the summer more sailing are expected. It is probably way too early to know the exact June schedule.