Recommended small cruise ship for Santorini/Crete/another island?

You have a good ferry system so you simply use that to move from island to island when you are ready to move. You are not going to find a cruise ship that will sit in Crete for 4 days or even more than one day. Also keep in mind that the islands begin to slow down, even shut down in Oct as the tourist population goes away.

If you want a small cruise ship, it will be expensive, as nowadays only the luxury lines have ships that could remotely be called small. And if you want to actually explore any of those islands, and really experience what they are about, then forget trying to do that from a cruise ship, where you'll be lucky to have more than 10-12 hours in port.

It would help if you listed which islands (besides Crete) that you want to visit. Others may be able to suggest ferries instead.

OTOH, if you think a cruise is more your style, then consider a cruise that includes both Turkey and Greece. But adjust your expectations accordingly. You definitely won't get 4 nights in Crete on a cruise.

Windstar offers smaller cruises of the Greek Isles.

https://www.windstarcruises.com/destinations/greek-isles/

They don't spend a lot of time anywhere. Personally, I would take the ferries as Frank suggested. This way you can make your own schedule. There are also flights between some islands.

Celestial Cruises are very affordable. As few as three or four days.

Thank you all for your advice. After reading responses and researching I will fly out of Istanbul to Athens 😀