Travel by cargo ships was a "popular" option to get around the planet
many years ago. For well-heeled alternate travelers,
in the know.
I say that because the fares then were nearly as expensive as going on a typical cruise ship, (sometimes even more so). Cargo ships used to have a special cabin or two for the odd adventurer. The food was excellent, the accommodation extremely good. But no "entertainment" included. And no guarantee of any exact itinerary. Depended on the cargo and ports of call.
There were several notable cargo shipping lines that offered this alternative, (especially Dutch ones). I don't know about these days. I would try and contact shipping companies directly for further information.
I remember an old travel book that was specifically devoted to this subject. Back in the 1970s.
