Acheron

Acheron is an ocean of living souls located south of known land. It is directly connected to River Styx by smaller streams, and it is possible that the River begins from Acheron. Uniquely, Acheron is paradoxical, and multidimensionally unstable. Traveling on Acheron will cause such a traveler to come back to the shore they entered the ocean from, no matter which direction they were going.

Because of this, Acheron is incredibly unexplored, and its aquatic flora and fauna is completely undocumented. Also, physical contact to the liquid in Acheron causes the bio-matter making contact to age extremely quickly, to the point of tissue death.