The river crossing riddle is described in this video (it’s okay to play it, it will probably stop before revealing the solution):
The rules (from the last part of that video):
- The raft needs at least one animal to paddle it across the river, and it can hold at most two animals.
- If the lions ever outnumber the wildebeest on either side of the river (including the animals in the boat if it’s on that side), they’ll eat the wildebeest.
- The animals can’t just swim across, and there are no tricks; the animals have to use the boat as described.
I wanted to figure it out, so I made a simulation. And I chose this particular lion picture because I’m pretty sure it’s the lion picture my daughters would choose: