Oceanography, the study of the oceans, is a combination of the sciences of biology, chemistry, geology, physics, and meteorology.

Ancient explorers of the ocean were sailors and fishermen who learned about marine biology by observing the sea life and discovering when it was most plentiful. They observed the effects of wind, currents, and tides, and learned how to use them to their advantage or to avoid them. These early humans discovered that salt could be retrieved from seaweed and grasses.

Polynesians combined what they knew about the weather, winds, and currents to investigate the Pacific Ocean, while the Phoenicians, Greeks, and Arabs explored the Mediterranean Sea. The early Greeks in general and Herodotus (484–428 B.C.) in particular believed that the world was round. Herodotus performed studies of the Mediterranean, which helped sailors of his time. He was able to take depth measurements of the sea floor by using...