Yes, within 1 day you can board as many ferries as you wish.  Cheers

is that actually true? I’m reading on this page here for Blue Star Ferries and it says the 4 and 6 day island pass gets you only 4 trips, not 4 days? https://www.interrail.eu/en/plan-your-trip/trains-europe/ferries/blue-star-ferries

Yes, the Greek Islands pass uses travel days and not trips. The page about Blue Starr ferries seems incorrect in suggesting it's trips that they count.

Also see the Greek Islands Pass page and the Greek Islands pass brochure.

@rvdborgt Did you get an email back from attica? I want to buy 5 greek island pass tickets and have tried emailing them about reservations, but I have not heard back from them. Any info you might have will be greatly appreciated.

I booked with them via e-mail pre-corona and back then they usually replied after 1 business day.

You could also try calling them

@rvdborgt thanks for your response! Now I am not sure if I should purchase online because I won’t get the passes in time, I travel in 1 month. I think another option is to purchase in person at a place in Europe like Paris or Madrid? Apparently you need a  # that can only be obtained from the actual paper pass to make a reservation. What a mess this is… any help would be greatly appreciated. Thanks again

The better ALT is simply to buy tickets when there-as >90% of people do-just as on a local bus. Dozens of ticket sellers in ports of any GR porttown/island. The savings with this pass are maybe just a few€-and thats all you get-plus many limitations on which ferries to take.

@mcadv thanks, I read other conversations where people are commenting about not being able to find them at the ports. If I do wait to buy last minute at the port, reservations are via email or over the phone. Not sure if I will have good reception and the patience to wait for replies with kids with me, I’m traveling with my 3 children and a couple of friends.

I’m going to answer myself on this one, after so many questions and so many run arounds… The paper pass is hardly avaiable anywhere. You need to order yours and cross your fingers that you ever receive it. It’s not being offered electronically or digitally now, OLD SCHOOL paper version only in which you need a code from the actual pass to make a reservation over the phone with someone in Greece. EURAIL website, Please add this info on the website and stop wasting our time.