Exactly what form of proof of vaccine did they require to avoid onboard testing, etc.?
I don't know .
But I would guess the price of buying a counterfeit Vax document went up; because the Cruise Lines are charging the unvaccinated for tests, making them wear masks, screwing up the unvaxed shore excursions, and exercising discrimination onboard.
That is why I wonder if this keeps up , how will they fill the many Cruise ships to capacity, if you have second class unvaxed cruisers paying as much, or more to go on a cruise. -Tom