Oceans cover more than seventy percent of the earth. Below the surface of the water lies chains of volcanoes, deep trenches, and tall mountains, whose tops break the water in the form of islands. Above the surface, oceans affect the earth's weather. Wind and water can create severe storms, depending on the temperature. The Gulf Stream, a current that begins in the Gulf of Mexico, travels across the Atlantic Ocean and affects the climate in the British Isles. Oceans are an important part ofthe planet. This basic introduction explores oceans form their formation millions of years ago to the important role they play in nature each day.