6 day greek pass travelling domestically and internationally same date

What does it say? Could you please post a screenshot of any error message or of where you get stuck?

It just does not let me select the 2 June date for the second travel day i.e. travel day 6. I can select other dates but not this one. I am assuming because I have already selected it for travel day 5.

I think there are a couple of issues at play here, and you might want to contact the Interrail folks directly to get this cleared up.

From what I can see, the problem you are facing is that you want to make 2nd June your 5th *and* 6th travel day.  The app won’t let you make it your 6th day because it’s already a travel day.  Logically that makes sense to me.

I think there’s some sort of assumption that you can’t travel on a domestic route on an international travel day.  If I was to guess, I would say that an international travel day would also allow for domestic travel.  It’s a bit like the way you can travel in a 2nd class compartment using a 1st class ticket.

I had a look at the terms and conditions for the 6 day Greek islands pass and it doesn’t state explicitly that you can or can’t travel domestically on an international travel day, but I expect that you can.

As above, contact the support folks directly and they should be able to clarify this for you.

In abstract terms, it would make no sense if I could only go from Patras to Brindisi on my international travel day and couldn’t get to Patras from <some Greek island> on the same day.

Yes that makes sense  however the terms and conditions say

• Includes ferry trips within a one-month period: 

          - 2 out of the 6 travel days can be used on international routes between Italy and Greece.* 

          - 4 out of the 6 travel days can be used on domestic routes within Greece.**

So I am unsure if I can use an international day as a domestic day as well

It is not very clear 

Has anyone done this

If you do 2 ferry journeys on one travel day, then I what's stopping you from doing so? I'd say you don't need to activate another travel day, as you wouldn't for a second train on the same day either.

Thanks very much that is what eurail have said to do however it gives me only one ticket for the entire trip which seems odd as if I get this scanned on the first ferry it may then be expired and won't work on the second ferry.

Maybe that is how it works and I can show one ticket for the 2 journeys as they are shown as combinesd.

Thanks for comments