Help me out everyone, I've got this idea for my setting that the river, maybe just for thirty minutes a day, can be sped up to hit speeds of 30 mph, and that a ship could ride that current from the source of the river out to the ocean or to any stop along the way. But how do I do it and what are some of the implications that I maybe haven't thought of? The most obvious problem is that it takes a lot of extra water. I was thinking the water would come from a massive natural geyser in the mountains, surrounded by a system of dams that would let people control how the river is affected. What else would I need for that to work?