There was no shortage of water on Demon Island. However, there were many types of water that humans could not drink. Only plants could absorb it. There were many animals on the island as well. Compared to the magical animals, there were more ordinary animals on the island. These ordinary animals lived on plants.
However, Demon Island was not suitable for human survival, and there was not much water for humans to drink. Apart from the small lake, there was very little water for eating in other places.
Under such circumstances, Zhao Hai used his ultimate weapon, the bottle tree and baobabs. The rain on the island was heavy, giving the bottle tree and baobabs room to grow. Zhao Hai even wanted to research and improve the Atlas tree. Of course, that would be a story for the future.