"The seven rivers are said to flow into the jaws of the God Varuna , as into a surging Abyss"
The above statement taken from the extract , is a very important clue to the existence of some sort of Abyss in the North Polar region , which I suspect is from the perspective of the Hollow Earthers observing their 7 Hollow Earth rivers "falling up" into the outer (Arctic) ocean...!
Regards