The Sand Sea is a vast ocean filled with quick sand that is located outside the kingdom of Thundera.
After the death of Claudus, Lion-O became determined to avenge his father by killing Mumm-Ra and he believed that the demonic being resided past the Sand Sea. This saw him meet with Koinelius Tunar and his Fishmen as they attempted to slay the Ramlak that had consumed the water of their oasis home. Ultimately, Captain Tunae was killed by the creature though Lion-O managed to slay the beast whereupon the stolen water was let loose for the surviving Fishmen crew. Seeing how revenge had consumed Tunar, Lion-O decided to travel back and find the Book of Omens rather than seek vengeance for his father.
- Given its nature, proximity to Mumm-Ra's lair, and the nearby field barrens with daggerlike rocks. It seems to be the new series equivalent of the Desert of Sinking Sands.