Schengen limit

I would think the answer to your question depends on where your cruise began, where you’re from ( US citizen, UK citizen, EU, or non- EUcitizen) and where you will be going after the last port.

Will you be flying home from the the last port, or are you planning to travel to a non- Schengen country?

Private, small boats have to “clear out” of Schengen. I know a guy who had to clear out of peninsular Spain on his way to the Canary Islands so that his sea days wouldn’t count as time in Schengen.

Admittedly I have no idea how I would go for a cruise ship. I wonder if the Cruise Critic forums would be a better resource for this question.

If your cruise is continuing on to non schengen ports, then that would be your last day in the schengen zone.
But remember, if your cruise is a transatlantic, that the Ports in Madeira and the Azores are also part of Schengen.
Your passports should receive exit stamps - either the ship will collect and hold your passports to facilitate this, or you will be notified to present yourself to immigration authorities to do this.

Where do you go after Portugal?

Cruises operate be somewhat confusing rules, and can have special arrangements with ports.

If your cruise starts and ends in the Schengen Zone, then possibly, even if visiting a non-Schengen port or in Non-Schengen waters, all days could be considered Schengen. At a port, you may be given cruise documents to wander the port, not your passport, or not go through any passport control. So technically, you were never really there per your travel documents.

Same thing with trans-Atlantic cruises with a stop, will you go through passport control or not? If not, then no real record.

Basically, you want to know when you go through passport control, those are the start and stop points. Your specific case, maybe more information on the itinerary would help, but even then, there will be a couple possibilities.

Your passport should be stamped when you enter the Schengen zone and will be stamped when you exit the zone, hopefully. Sea days during that period of time are considered being in the zone. Is Portugal your port for disembarkation?

Are you counting your day 1 as the first day of the cruise or is the cruise arriving (with you) into Schengen from non-Schengen, say England or USA? Or if your day 1 of the cruise, it that the same day as your incoming flight arrives?

These are important questions for correctly setting your last day.

Welcome to the Forum, crvela66... just a little more info please to help most effectively...

Yes, more info would be helpful. But I get the feeling that the OP must be doing some land travel , or perhaps a series of back to back cruises if they have calculated their exit is 88 days in the zone.

We will be in Italy before the cruise. The last port in Schengen is on Dec 9 in the Azores and then we travel back to the US onboard the ship. I guess I just need to make sure someone "stamps us out" (?) on the 9th in Ponta Delgado since that is day 88.