CLOUDBURST by Tyree Campbell

In the future the Earth is warmer, and the oceans have all but dried up. In small settlements on the ocean floor, the remnants of humanity survive—traders and raiders. The few remaining books feed the campfires.  Monstrous lungfish inhabit the salt marshes and snare the unwary. Saltstorms across the salt flats destroy everything in their paths. Social divisions remain intact—men hunt and steal, women breed and struggle to preserve what little knowledge remains—and act as translators for the traders.

The finest of the translators is Praise, a woman of the Scarpers. Centime, of the Dobers, is her student. If the Scarpers and Dobers unite, there will be no need for translators, and Praise will lose what little independence her abilities command. She would rather commit suicide and die free . . . but Centime has another idea: to return up to the land, and to the stars that had been humanity's destiny.

Thus begins an impossible journey, fighting the raging tribes and the fury of the elements . . . for the very Earth itself seems to oppose the two women and the little band they have gathered.