Better horses than people, as was the case in Russia: https://en.wikipedia.org/wiki/Burlak

Inspiring a famous painting by Repin and The Song of the Volga Boatmen: https://www.youtube.com/watch?v=uNb54rwDQJM

You still occasionally see horses powering boats along canals here in the UK. Of course, they're pulling from the towpath, not actually onboard the boat.

https://www.horsejournals.com/popular/history-heritage/horse...

I suppose you could run the horses on a treadmill connected to a water wheel... but I’d probably stick with tow ropes.

The horse would probably agree.

Ulysses S. Grant mentioned this technology in his personal memoirs, in the context of his childhood.

"I kept the horse until he was four years old, when he went blind, and I sold him for twenty dollars. When I went to Maysville to school, in 1836, at the age of fourteen, I recognized my colt as one of the blind horses working on the tread-wheel of the ferry-boat."