We are thinking of taking the ferry from Sorrento to Capri, getting a cab to go to Anacapri for the day and back. Do we need to pre-book the ferry?
Hi - we didn’t go to Capri but went from sorrento to Naples and bought tickets the morning of without any problems. The ferry wasn’t even half full. It may however depend on when you’re going. We were there last week.
Your question needs the month of the year-this is high-intensity tourism. But in most cases, you can buy on the morning. Note that they will, wisely, want you to buy your return ticket for a specific time, at the same time. I noticed that there are several companies working at the Sorrento marina, so check schedules and prices in advance, if you care about whatever discretion you may have. They're not going to refer you to their competition around the corner.
After 4 visits to Sorrento, 2 in July and 2 in Oct., most recent visit last Oct., and visiting Capri 3x we have never pre-booked/purchased our boat tkts and never had a problem getting tkts for a say 9.30 or 10 a.m. ish boat. We purchase our return tkts at the same time for one of the latest returning boats but you can get on any earlier boat back to Sorrento regardless of the time on your tkt. Have a great trip!