I was in May there. The boat I was on had positive cases which were detected when people got home. With some reason(!) the tests done to clear the borders on last day were all negative.
This was at a time most people were not yet fully vaccinated, so most of us had to take a test to return home.
General rule was if 1 person is infected, everyone goes onto quarantine including the boat crew. If everyone is vaccinated and they can return home without pcr test, chances are that nothing will be detected due lack of testing.
Cruise manager of the LOB I was on, told us about the conditions of the quarantine and it did not sound so great. Poor food, bad internet, allowed very short time to get fresh air etc. Nevertheless I plan to visit there again Jan or Feb again. I did get an insurance for it last time and I would do it again.