The River of Mist

The River of Mist (Or Fog, call it whichever you want) was once a gushing torrent of water blasting down the central valley of Strylight's below-sea-level areas. Since then, though, it has been dammed in order to satisfy the need for fresh water at the then-tiny Aquatic Town. Since then, the Town has become a paradise for water-type users and normal humans alike, a River on the other hand...

Has become a tiny trickle. The damper climate in the valleys does not help much either, and the canyon it was in has become thick with mist which just sits there. The mist does not go much higher than the edges of the canyon, though, so it is safe to travel along the walls of the River.

Be wary anyway, as those who have gone down into the Mists have a tendency to not come back out.