Bismillah hir Rahman nir Rahim.
Someone who keeps thinking about the planet on which he lives, thinks how important water, which Allah creates, is for human life. The following comes to mind: people, in general, understand the importance of water only when they are deprived of it for a long time. Water, however, is a substance which we need every moment of our lives. For instance, a considerable portion of our body cells and of the blood that reaches every point in our body consists of water. Were it not so, the fluidity of blood would decrease and its flow in the veins would become very difficult. The fluidity of water is important not only for our bodies but also for plants. Thus, water reaches the furthest end of the leaf by passing through its thread-like vessels.
The great quantity of water in the seas makes our earth habitable. If the proportion of sea to land on the earth were smaller, then lands would turn into deserts and life would be impossible.
A conscientious person who thinks about these matters is completely convinced that the establishment of such a perfect balance on the earth is surely not a coincidence. Seeing and thinking about all these shows that a Creator Who is exalted and the owner of eternal power created everything for a purpose.
Ref: Excerpts from Tafsir Ibn Kathir & The Glorious Quran: Translation by Abdullah Yousuf Ali.