A vast sea. It is reachable using a teleportation formation hidden in the Great Jin. The Five Dragon Seas is hinted to be a sea with many cultivators such as the Scattered Star Seas, not much is known about this area except for a few times it was mention.
After Han Li got trapped in the Umbra Realm, inside one of the village while inspecting the crude and unusual Formation that releases the Purple Qi that protects the village from the dense umbra Qi fog he met a cultivator from the dragon seas who mention that was his home before been trap, he also directed Han Li to the residence of a former trap Nascent Soul cultivator who died years ago, this cultivator left his legacy on tablets during his down time.
Another time the Five Dragon Seas were mention in details was after Han Li became a Deity Transformation powerhouse. About 150 years later, Xiang Zhili discovered a spatial node located in the Five Dragon Seas and he entered it together with Eccentric Feng, Hu Qinglei and Old Demon Che. Before he leave he left instruction for Han Li, he would later enter the Five dragon seas where he met a few cultivator including the beautiful Fairy Bi.