Fell down the rathole of researching travel by ocean freighter. As best I can tell, it's a doable proposition. But it's not one I'd recommend, even to those who want to avoid air travel.
* Expensive overall
* Limited time in each port, maybe no time if captain is behind schedule
* Long voyages
It comes down to: Are you into ocean travel for it's own sake more than being a tourist? If the answer is 'yes', this kind of travel is for you.
But it doesn't have to be that way!
The problem is, there is no reasonable way to book a trip with a week or more in each port, even through most routes have weekly or biweekly sailings. All booking is done one-way or round trip with the assumption you'll spend most of your time being a passenger.
The passenger/freighter lines could book passengers in rotation on each route, with layovers at selected ports between sailings of different ships. This would work well for someone with the free time who didn't want to fly.
And with many of us wanting to travel, but not wanting to fly a polluting airplane, there is probably a good market for that kind of thing.
But passenger/freighter ships are limited to a max of 12 passengers because they don't have a ship's doctor or meet other requirements for cruise liners. So they probably don't have any trouble filling berths with the way they currently operate and see no reason to change.
After all, some people like the voyage more than the destination.
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