I made a river with realtime fluid flow physics. Notice the objects moving following the water flow, even backwards and in circles. The flow can change dynamically with some randomness so you sometimes get big waves pushing the objects along. Also the objects obstruct the flow but also get affected by the obstructed flow giving it a bigger push.
Also simulated underwater current which reduces with depth until zero on the river bed. And googling which fruits float and which don't (it's not immediately obvious).
Can’t wait to make a boat.. whitewater rafting here we come!