Oceanography
Oceanography is a branch of earth science that deals with the ocean. It includes such things as geological, biological, chemical, and physical oceanography.
History
People probably traveled the seas since prehistoric times, but the first westerners known to have learned how to navigate were the Phoenicians, who may have explored as far as the British Isles.
The Greeks view of the world was demonstrated by Herodotus, which included Europe, Asia, and North Africa, all of which were surrounded by a large river called "okeanus." Longitude and latitude were both developed by the Greeks. Pytheas discovered that in the Northern Hemisphere, one could use the angle between the horizon and the North Star to find their latitude. Eratosthenes used longitude in his maps, though the lines were placed irregularly so that they could pass through important landmarks. A librarian named Hipparchus later placed lines of longitude at regular intervals, and this was improved even more by Ptolemy, who added cardinal directions and divided degrees into minutes and seconds.
Besides navigation, Eratosthenes also measured the Earth's circumference fairly well. Research into physical oceanography included Strabo, who observed volcanic activity and concluded that land was not totally static. He also realized that streams eroded continents and deposited sediments into the ocean. Posidonius took a depth sounding of the ocean, while Pliny the Elder related the moon's phases with tides.