People in the diving world have described the ocean as "the world of inner space." You leave the land and enter a gravity-free state. As you descend the sunlight thins, and your sense of distance and direction are distorted.
潛水界向來稱海洋為「內太空世界」，離開了陸地，處在無重力狀態下，隨著深度下降，陽光遞減，人的方向感與距離感都不再真切。