If getting the excursions you want in English is important, I do not recommend booking with Costa in the Mediterranean.
We were attracted to a Costa Magica cruise in the Western Mediterranean by the excursions and immediately after booking the cruise, pre-booked an excursion in every port. Eventually we got every cruise we had pre booked, but it took HOURS and HOURS and we had to aggressively negotiate to get them.
Prior to departure, we got an email confirming our selection of excursions, saying that the tickets would be delivered to our room and that we wouldn't need to stand in line. If only that were so.
Immediately, after boarding, we went to the excursion desk, because the system had let us book an excursion in Barcelona, which was our city of embarkation and disembarkation. We were concerned that we would be booked for a tour we might not be able to take. If only that were the only problem.
Turns out that we couldn't take a tour in Barcelona and would not be charged, but the rest was bad news. The excursion desk told us that they could only confirm that the first 2 of our 6 excursions would be offered in English. We were told that the tickets for those two tours would be delivered that night after 8 PM. That evening, long after the excursion desk had closed, we got a note in our mailbox saying the next morning's excursion had been canceled and that we should show up the next morning to pick a different tour. I went to the hotel desk and demanded to speak to someone about the problem and refused to leave. An hour or so later, they finally agreed to send us on an Italian bus to Avignon and Les Baux with one of the excursion staff translating for us.
We later met a couple, who had booked the same tour as we had to Avignon and Les Baux, but had it canceled. They didn't protest, so they didn't get to go.
Every day was a new negotiation and a new headache. On the third day of the cruise we were at sea in the morning, so I went to the excursion desk to see about the excursion for the next day. They said it still wasn't clear that the tour would run in English. That evening after returning from the afternoon excursion, I waited in line at the excursion desk for an hour only to be told that there was no problem with the three remaining tours and that we should have already received the tickets. They said that "room service" was the problem and that I should call room service. Room service denied all, so I was back in line at the excursion desk. This time they agreed to write out handwritten stubs. The next day at lunch on our tour, they gave us the stub for that day's tour and the tickets for the next two days.
Literally, we never knew if we would get the tour we had picked until the bus rolled out. One morning, we were the first in line, but were assigned to the second bus, which had a label for a different tour.
Only about 5% of the passengers on the cruise had English as a first language, so it was no wonder that there was a problem getting English language excursions. Our fellow English speaking passengers were more mellow about the canceled tours and often didn't get what they had requested.
I thought it would be fun to be on a boat with other nationalities and multiple languages being spoken. I like Italian food and in particular love octopus and squid. I just didn't realize that the number of English speakers would be so low that having excursions would be a problem.
I have to agree with Paul on this too. I was aware of the issue the OP described, luckily we had a roll call going with other english speakers and most of us decided to go on two of the same excursions, since there were a few of us, we had a reasonable expectation that our tour would be fine because several of us signed up for them. The rest of the ports we happily navigated onour own, with few issues, except of course for the pushy cab drivers in Palermo .