I posted this under my live review of Scenic Mekong, but thought it might be of interest on this thread as well -    Follow up on the Vietnam visa situation. Many itineraries, whether on your own or booked as a package through the cruise line, require you to enter Vietnam multiple times (rather than single entry). For example, we started in Hanoi, then on to HaLong Bay, then Hoi An, before we flew to Cambodia to start with Scenic. We then entered Vietnam again yesterday afternoon,