The Sea of Blood
is a dangerous place found near the Wastelands
in the Realm
This entire lake was filled with blood. The souls of the dead that are there are put to use with their bodies added to the sea of the blood of the damned.
Those that traveled the sea through boat were often challenged by bloody Undead skeletons that boarded their craft and attempted to kill the living.
During their quest in Mortal Kombat: Shaolin Monks, Liu Kang and Kung Lao traveled across it with the younger Sub-Zero.