Well, presumably being at sea in a non-stressful environment would have some chance of not causing that.

I'm not sure what such a thing really looks like, mind (luxury cruise passengers don't usually live on the boat long-term) or if it's feasible to talk about it within the space of current nautical engineering. I certainly have never been on a boat that didn't feel like a fairly controlled, sensitive environment in which one couldn't just relax without having to keep tabs on everything else, but my experience is limited to fishing, crabbing and similar boats, which are very high-stress environments if you're doing more than a quick excursion, especially in the waters I'm familiar with.