Bob Shaw 
Medusa’s Children [EPUB ebook] 

What unfathomed secrets lay sleeping in this eerie world of water?The Clan knew almost nothing about the giant sphere of water they inhabited, and even less about the sun and planets nearby in space. Living amidst a cluster of nets anchored to the roots of a giant plant, they were aware only of their unending quest for precious air bubbles; and of the unending threat from the ever-hungry Hora. Those who fell victim to the beasts’ voracious tentacles were left to sink slowly to the depths, where an awesome and unknown being awaited them. He was the greatest mystery of Clan existence — until that is, the world began to change, until the current began to draw the city down to the realms of Ka.