This entire thing gets really confusing. We are from Florida, and went through on-board immigration in early December. If you leave from San Juan (U.S. Territory) and then stop in St. Thomas, no on board immigration, but if you stop say in Dominica first, then St. Thomas, then you do have immigration. Same holds true for Florida, when ships stop at their own islands 1st, and then St. Thomas, immigration again. You want to look at St. Thomas being your 1st port, but unfortunately, that doesn't always work. It's annoying, but very easy, basically a walk through to check passports, etc. Hope this helps.