There are these ultra-luxury boats that folks rent from time to time. They go off on these ships and do whatever and then return them from whence they came. The folks who stay the same (for a while anyway) are the crew. "Below Deck" focuses on the crew, the folks who service the millionaires who rent the boat. The crew get to visit great places and see things they might otherwise never see. But, we suspect they're not always treated very well. We get to see how they live on this new reality show. Think of it like "Upstairs Downstairs" on a boat.