So, this game has managed to impress me to an extent that no game in a very long time has managed to do. There's fluid dynamics with the water. The current isn't just stationary; you can change it, and to a massive degree.
The traffic is based more closely on real traffic than just about any other city builder I've ever played; an emphasis on actual traffic management rather than the ridiculous "add more lanes and everything is solved" mantra of classic Sim City games.
The data views... holy hell those are shiny. When you start building huge mass transit systems, just watching the people waiting for the next subway train after getting off their train into town as they go about their business... it's amazing. Everything about those data displays is just about perfect. Even the traffic light colors are animated and correct to the flow of traffic.
Even subtle changes to the flow of the fluid as the intake and outlet pipes pull in or push out small amounts of liquid.
Now for the meat and potatoes of this post:
FLUID DYNAMICS HELLS YES.
So, by building dams, you can dramatically alter the flow of the water. I highly recommend playing around with that. As for me, I went on the (diamond something or other map) and after some experimentation, bought up the mountain peaks on either side of the little river near the starting block.
Fun fact 1: the height of the dam is based on the end points it is created with.
Fun fact 2: the flow dynamics in combination with the way the dams work (not letting water through until the reservoir behind them is mostly full) means that water will fill up behind them up to around the height of the dam.
I think you can see where this is going. It was glorious.
In that last image, the water was actually flowing downhill into a localized depression on the other side of the city; it was actually flowing quite fast, looking to be comparable to the speed of a car.
A good portion of the city flooded in the end, then windows updates decided it would like to reboot without warning, ending the experiment (it would never have fully filled, since there was a great big open plain with a low slope upriver)
Oh, and another fun fact from some separate experiments: You can get dams to force water uphill. It detects the direction to face them based on velocity of the water; which is easy to reverse in the short term while placing a dam. By doing this repeatedly with tiny dams, you can push water uphill as the dam sucks it in on the intake side and spits it out on the (uphill) output side.