Britannica Educational Publishing 
Oceans and Oceanography [PDF ebook] 

Constituting more than 70 percent of Earth’s surface, the world’s oceans are so vast as to remain something of an enigma to this day. Navigating these imposing seas and unlocking their secrets is the calling of oceanographers. Their research helps determine what climatic, geologic, and chemical impact oceans have on a variety of organisms. In spite of their magnitude and might, the world’s oceans are not immune to the effects of adverse human activity, such as pollution. This volume surveys this huge, but fragile, ecosystem and the individuals who help fight for the preservation of this vital resource that has critical significance to all earthly life.