The sea, the world ocean, or simply the ocean, is the connected body of salty water that covers over 70 percent of the Earth's surface. It moderates the Earth's climate and has important roles in the water cycle, carbon cycle, and nitrogen cycle. The most abundant solid dissolved in sea water is sodium chloride.
“The nature will drag us deeper and deeper, further and further.”
Although the sea has been travelled and explored since ancient times, the scientific study of the sea—oceanography—dates broadly from the voyages of Captain James Cook who explored the Pacific Ocean between 1768 and 1779. In geography, "sea" is used in the names of smaller, partly landlocked sections of the ocean, for example the Irish Sea, while "ocean" is used in the names of the five largest sections, such as the Pacific Ocean.
