Hi we just went through this on the Carnival Panorama sailing to Mexico last week. Upon arriving for embarkation there will be a separate line for those who need to be tested to have that done. You’ll wait until your results are shared, and proceed with embarkation like everyone else. On the second to last day of the cruise you’ll get a note on your door asking you to come to a testing spot on the last full day of the cruise. For us it was a conference room where they will administer antigen testing. After that they’ll ask you to stay in your room for 30 minutes, no news is good news, and other than that carry on with enjoying the rest of your cruise. We didn’t get a positive result, so I’m not sure what the outcome would be should that happen. Also, I was under the impression this would cost an additional $120 for both tests., but it wasn’t in our onboard account and I’m not really sure if it’s been charged yet or how. I’ll follow up once I figure that out.