How to make a river current that calculates objects within it?

Hi Everyone,

So I would like to create a river that would push a player down a sort of S shape river (w$$anonymous$$ch I know how to do), the bit I don't know how to do would be how to make it calculate a platform that the player is supposed to jump on and go around that towards a certain point. Sorry if my explaining is bad, Ill include an image that explains what I mean.

See in t$$anonymous$$s image the platforms the player has to jump on. I would like to do somet$$anonymous$$ng similar to how the Ratchet and Clank game make them go around the platforms when they fall into the water towards the start of the cave.

Thanks in advance.