My vote goes for Maldives, on a 2 week liveaboard going to the extreme south to see tiger sharks. Good for experienced divers because strong currents and big wildlife. Tropical, and a long history of dealing with COVID (and a highly vaccinated population, especially in the tourism sector). Spent a month in Maldives April-May 2021 and was supposed to do the itinerary described above, but the guests on the boat from the previous trip tested positive, so we had to get a different boat and do a different itinerary.