The lagoon was surrounded by fields of Dragon Bone Grass that grew in thick clusters. Yang Ling tried to transport some of the grass into the space with the Wizard's Pagoda, but it took a lot of energy. If it took that much to move some Dragon Bone Grass, he wasn't sure he would be able to move all of it. He'd never get the whole lagoon transported even if he exhausted all of his mental energy.
After repeated attempts, Yang Ling realized that he had to spend the same amount of mental energy to transport a can of water from the lagoon as transporting twenty blades of Dragon Bone Grass. There was an abundance of Dragon Bone Grass, but the amount of water in the lagoon was unimaginable.