The water is filled with skeletal fish that will only attack if they can see them straight in front of them, as they can't see behind them or sense anyone or the water move. They're also very slow to turn around, so sneaking past them shouldn't be a problem.

In the distance, there are some stone walls, far below them, as well as ruins of a what looks like a town that surrounds a castle.

And swimming skeletons with spears and swords.