If we look at other planets and see the evident lack of any developed life forms, we can also see that they (at least at this time) do not support any large bodies of water. Although man has had a long association with the sea, especially through fishing, it was not until the late 19th century that he really began to study the complex world of this watery realm.
世居陸地的人類，雖然很早以前便會航海、捕魚，但對於海洋的瞭解只是代代相傳的片段經驗。一直要到十九世紀，在殖民主義擴張領土的背景下，海洋才成為人類新的探索對象。