Did it this past week on a carnival cruise. First off make sure you have every documentation that is required with you.....death certificates cremation records, etc, etc. Have the ashes in the appropriate vessel. When you board go to guest services with your documents and they will set you up. It's only done on sea days anymore as I understood it. You'll agree on a time and we got a letter in our cabin the next day confirming the details so check them over and call/stop in and let them know it all looks good. Day of we met at guest services and security and a gentleman in a white shirt took our group down into parts of the ship the mooring lines are kept/go in and out of. They were doing some maintenance down there but they stopped and left. Another individual met us there and took us to the side of the boat, opened up what I'll call an opening with grates over it up on a ledge that could hold four people or so and it was done. Nice, respectful, well done event. The next day we got a nice signed letter from the captain in a book that had all the important information like date/time/latitude/longitude. Pretty easy to setup and nice follow through by Carnival.