Sea of Clouds

Below all those that float through the skies, lies the Sea of Clouds. It may resemble the clouds in the skies, but is nothing like them. The skies may reveal sun and stars, but the Sea of Clouds shows nothing. Where a normal cloud may form or dissipate, the Sea of Clouds is eternal and stretches on as far as one can see.
Little is known about the Sea of Clouds. What people know is that anything that flies too close to it, will be swallowed whole and never return. Birds, ships, even entire islands have been swallowed as they sunk too deep. One of the greatest sins one can commit, is throw anything or anyone down, making sure that they are lost forever.
As to The World Below, nothing is known, only tall tales exist.