Amenities on permanently moored ships - how to map the ships?

There are multiple river banks/strands in Prague, with permanently moored ships. Onboard those ships are various amenities (restaurants, pubs, hostels/hotels, a theatre, etc.). However, only the amenities are currently mapped, which leads to misunderstandings ("Pub in the river? How unlikely, let's armchair-move it over to the strand.").

I would like to map those ships - they have been there for years, there is no intent to move them, and are even incapable of moving elsewhere. From a pedestrian POV, they are essentially a connected set of area=pedestrian and highway=steps; however, that does not seem as complete or correct tagging to me. They are otherwise unremarkable refitted coal barges, so historic=ship is inappropriate. One of them is mapped simply as building=yes, which is OTG-ish (as large as a medium-sized building, with one or more floors, doesn't move, serves a similar purpose), but doesn't seem appropriate either.

So, what is a good combination of tags for such floating almost-buildings?