It's a Vansky Inflatable Lounger. Basically it's a big air bag sofa one sits or lays in. Un-Inflated it folds into a small pack making storage on board easier. If you can find space on board it looks like it could replace the hammock, bean bag and beach chair. I like that it is available in various colors. I personally like the Orange one for the boat so it might be able to be used in an emergency rescue situation. It requires no pump and is cheap enough it will not make too much of a dent in the cruising budget.
Here is a fellow checking one of them out: