My husband and I are traveling by ferry from Crete to Santorini, Santorini to Naxos and finally Naxos to Mykonos the last two weeks of August.
Is it advisable to pre-book our ferries, and if so, which web site offers the best fares?

The best fares will be found on a ferry company's website. Ferry schedules: www.gtp.gr You don't need to pre-book. Just find the ferry company's ticket seller/office on each island and book as you go.

We are going to Greece again at the end of October; and are taking a 7 day island cruise stopping at Mykonos, Santorini, Patmos, Rhodes, Crete. The dates are nearly all sold out except for a couple dates in November. While that is a different form of island hopping, I don't know how individual ferry rides are but would imagine they are full or getting full - esp since you are going at the end of this month (high season). IMO, I would look into pre-purchasing if possible, or certainly getting tickets for the more popular routes, just to be safe.....

thanks!

Thanks!

I took ferries between Santorini - Folegandros - Milos - Sifnos - Santorini during July and and most of those trips the ferries were full. Those were the Sea Jets high speeds. Maybe the slower larger ferries don't get as crowded but if you plan on taking any high speed ferries I'd book them ahead of time, especially for August.

I just checked my trip report form 2011 - we bought our tickets at Amphitrion Holidays in the airport and had no problem. However, we were there in mid-September to early October, which is much later in the season, so I wouldn't give advice based on our experience.

If interested, here's my report from the same places. We didn't make it to Mykonos, though. We had planned to do a one-day ferry tour to Delos and Mykonos from Naxos, but it was canceled the days we were there due to high winds (end of September).
My Greek Diary - September/October 2011

We were just there in June. You don’t have to pre-book, as you can buy your tickets at the respective ticket agents. However, I’m a planner and I did. I think it’s important to be aware of the different time schedules so you can decide which ferry is best for you time and price wise. Also, pre-booking I did find it to be cheaper. I know this because as I went to the ticket agent to print my tickets (you have to go there and they charge you a fee per ticket to print- what a scam), someone arrived to buy a ticket. As I overheard the purchase, I realized my pre-booking was cheaper than that person who walked up to buy hers.

Hope this helps!

I was NOT charged anything to print the tickets I had pre-booked.

I was in both Paros and Naxos- €1 per ticket to pick up and print them by the ticket agent.

August is the busiest month for tourism in Greece so I would pre book.

We were travelling in the Greek islands in August a few years ago and it was jam packed. Also extremely hot. We pre-booked ferry tickets and picked them up at travel agents as we went along but didn't have to pay anything extra. One thing I would say is double check the ferry departure time the day before as they can change. We were going to get up around 5am for one ferry but found out late the night before that it was leaving much later at about 10am. So glad we found out, the hotel let us know in that case which was nice of them.

Also before booking, check where you can collect your tickets, sometimes it is Athens which in your case would be extremely inconvenient

Kay

Many thanks to all who replied to my query RE pre-booking ferries. So helpful!

I'm pretty sure Amphitrion Holidays is no longer selling ferry tickets at Athens Airport. Try Aktina Travel instead.

Again, thanks to all who replied. I wanted to pass on what ultimately worked for us. We were rushed in the Athens Airport so couldn't deal with ferry tickets then. However, our hotel (which was great BTW - Elia Palazzo Hotel in Chania) referred us to Kyriakakis Travel in Chania who issued paper tickets for all of our island hopping at the same prices I saw online. They were very efficient and even took our hotel info so that they could inform us if there were any cancellations or delays. Highly recommend if Chania is at the start of your trip.

That's great that it worked out well for you. Love Greece, hope we get back there one day.

Kay