The term 'Of the Great Seas' refers to the OCEANIC body of water that covers most of the Earth's surface. The word 'OCEANIC' is a seven-letter word that describes this vast body of water, which is composed of five major oceans: the Pacific, Atlantic, Indian, Arctic, and Southern Oceans. These oceans are connected by smaller seas, such as the Mediterranean Sea, and are home to a wide variety of marine life.