You swim down the river and get to a place where there is a lot of current. There is something that looklikes dark blue light if light can be dark. A voice is coming from it:
You are between the devil and the deep blue sea. You can swim to the devil, in that cave, and kill some fishes to get food, or you can swim to the sea and there it is the same, just that you would have to kill different fishes. Where would you go?