The universe was very vast. Sometimes, it would take thousands of years just to travel it. That was why only Mythical creatures were qualified to travel around the universe. This was because Mythical creatures had an unlimited lifespan and could move at the speed of light.
However, Wei Huo did not plan on traveling alone this time. He brought Chen Xuanyue into the Leviathan's body. The Leviathan could be considered a huge biological battleship. There were many huge holes in its body. Some of them were warehouses, some were gas tanks, and some just contained land that could grow plants.
Besides, as long as one grasped the Heart of the Zerg of the Leviathan, one could modify its internal structure. One could even modify the Leviathan into a battleship that was half-mechanical and half-biological.
However, Wei Huo did not modify the Leviathan too much. He only obtained an ancient star chart from Kalan and entered the Leviathan's body to make it depart.