Has anyone hiked Vesuvius recently? Can you buy tickets at a ticket office there or do you need to buy them ahead of time online? Getting mixed info on that.
I've not done it but there's here's info on the park's own website and their ticketing service:
https://www.parconazionaledelvesuvio.it/en/visit-the-park/the-paths/the-great-cono/
It does state that tickets must be purchased online, and those tickets are purchased for specific open time slots...which appear to be sold out for today. Also:
"Tickets can only be purchased online. The internet connection close to the entrance is extremely weak or intermittent so visitors are advised to buy tickets before arriving at the open area at 1000 metres a.s.l. "
All-in-all, I'd say you need to buy them somewhat ahead of time.