Ocean exploration is a part of oceanography describing more generally the exploration of ocean surfaces. It is also the period when people explored the ocean boundaries. Notable include: the Greeks, the Egyptians, the Polynesians, the Phoenicians, Phytheas, Herodotus, the Vikings, and the Portuguese. Travel on the surface of the ocean through the use of boats dates back to prehistoric times, but only in modern times has extensive underwater exploration become possible. Scientific investigations began with such early scientists as James Cook, Charles Darwin and Edmund Halley. Ocean exploration itself coincided with the developments in shipbuilding, diving, navigation, depth measurement, exploration and cartography.
500-200 BCE Greeks developed trade routes in the Mediterranean using the length of the day (corrected for the time of the year) to estimate latitude.
450 BCE Herodotus publishes a map of the Mediterranean region.
325 BCE Pytheas, a Greek astronomer and geographer, sailed north out of the Mediterranean, reaching England and possibly even Iceland and Norway. He also developed the use of sightings on the North Star to determine latitude.
1698-1700 Edmund Halley made probably the first primarily scientific voyage to study the variation of the magnetic compass, sailing as far as 52 deg S. in the Atlantic Ocean. On a previous expedition to St. Helena, he made an important contribution to knowledge of the trade winds.
1768-1780 James Cook explores the southern parts of the oceans looking for the southern continent. He was the first to use a marine chronometer to determine longitude.