Underground River

The legend so long that's been told, and here goes, that where this underground river flows, It's always blacker than blackest night. And when you go in this cave you need a bright light. Way down under the earth in this cave, The fish are blind that swim in these waves, And some have even said, and that's no lie. that if you could catch one, they would have no eye. They are quicker than lightning, and they know, they must go as the river flows. They know where the banks are by their feel. and know the dangers of the river are very real. This river flows gently and is never too deep. It's stays most the same in cold and in heat. For you see the temperature is always the same. down under the ground and that is no game. This river keeps flowing from beginning to end, however, as far as we know, there is no end, my friend. So on it will flow, forever I guess. And if anyone finds it, it will be a success.