Let's be honest, it's hard enough worrying about what to wear in our daily lives, let alone on holiday – so fretting about cruise ship dress codes isn't ideal. However, assuming you're only going on one cruise at a time, once you get the low-down on any themed nights on the itinerary or the level of evening formality required, it becomes a lot easier to pack . On most cruise lines, some basic rules apply – none of which will surprise you.