Great Rivers of the World “O...-”
for social studies and science educators and home schoolers.

The Ob, a major river in western Siberia, Russia, is the world's fourth longest river. It is the westernmost of the three great Siberian rivers (Lena and Yenisei) that flow into the Arctic Ocean. The Gulf of Ob is the world's longest estuary.

The Oder River of central Europe rises in the Czech Republic, flows through central Poland forming a border with Germany and Poland, finally flowing into the Gulf of Pomerania of the Baltic Sea.

The Ohio River, formed by the Allegheny and Monongahela Rivers where the city of Pittsburgh was founded, is the largest tributary of the Mississippi. The Ohio serves the southern border of Ohio, Indiana, and Illinois, joining the Mississippi at Cairo, IL. The city of Cincinnati, Ohio is located on the northside of the Ohio, across from Louisville, Kentucky.

Numerous Native American groups built earthwork mounds in the Ohio Valley, de La Salle was the first European explorer in 1669, and it became a water highway for westward expansion.

Thomas Jefferson said “The Ohio is the most beautiful river on earth. Its current gentle, waters clear, and bosom smooth and unbroken by rocks and rapids, a single instance only excepted,” in fact the name Ohio is from the Seneca, meaning “good river”.

• Ohio River Valley Poster Map

Oise River, a tributary of the Seine River, has been the subject of artists such as Vincent van Gogh, Charles-Francois Daubigny, Camille Pissarro, Theodore Rousseau, Paul Cezanne, and Jean-Baptiste-Camille Corot.

Aerial View of Inland Sea Formed by Okavango Delta, Botswana, Photographic Print (18º57'43"S 22º29'04"E)

The Okavango River in Botswana has no outlet to the sea, it empties onto the sands of the Kalahari Desert where it forms the world's largest inland delta.

The swamp was once part of an ancient lake that dried up some 10,000 years ago, today it is home to wildlife and attracts thousands of visitors a year.

The Orinoco, one of the longest rivers in South America, watershed covers Colombia and Venezuela. Christopher Columbus discovered the mouth of the Orinoco on his third voyage (1498), the upper reaches weren't explored until 1951.

Aime Bonpland (1773-1858), a French army surgeon, explorer, botantist and professor of natural history who collected and classified plants in the Amazon and Orinoco River basins.