Restless Isles

Swirling endlessly around the Vortex are the Restless Isles, small islands moving islands, some no more than a few hundred feet across. These islands are the only land in the Deep Ocean. When the Altanic Isles or the High Isles lose buoyancy, many come floating down to the sea. Others crash down into the water. Although some remain floating, many eventually sink into the deeper reaches of the ocean, where aquatic humanoids dwell. 

Restless Isles

Everdusk WotC_GregBilsland