This is quite an old idea, actually - see the later Roman Empire (oxen, not horses, but still).

Yeah, they mention that in the write-up.

I still think the idea is pretty cool. As is the graphic. It's like a carousel, but... not fun.

Oh yes so they do! Teach me to read in detail. It is indeed a cool idea - I wonder how stable the boats would have been, but being a passenger would have been fun.

Hee.

They said they had two types -- one in which the horse walked in a circle, one in which he was on a treadmill (that's the one they show) -- and I was actually wondering which one would be more fun for the horse.

Probably neither of them, really.