The definition of a river can be a bit of a debate and a write-up on its own. I'm not going to argue that much; this exploration(pun intended!) will have a little of everything. I hope to point out a few things that could be new to anybody's level of knowledge.
Rivers, lakes tend to be the place for most non-fish like life to get their water. This goes for both Homo Sapiens and non-human species. It's an interesting thought to wonder how Human species might have gotten their survival skills from their evolution from non-human species millions of years ago.
Archaeologists/Historians of Human civilization have always noted that some of the earliest western civilizations generally grew up around great rivers - like the Nile and the Euphrates/Tigris. I've shown an Egyptian boat which was found, I think, in one of the Giza pyramids. Clearly, the Egyptians thought boat technology was of some significance. Summarian and Babylonian boats seem to be hard to find, but there is artwork showing them.
There's not much more to say about rivers and boats in Egypt and Mesopotamia. Sufficiently sophisticated boats however allowed some people to move somewhere else and settle down elsewhere. Islands would be a bonus as well as finding other rivers. We know the Minoans settled Crete a long time ago, and there's other places like Malta; there's Sicily where I actually lived during part of my own youth. Civilizations came and went. Historians generally consider the Phoenician's to be a great sea-faring people. They made it out of the Mediterranean sea(kind of a large river? Or a large lake?). I've found an interesting tidbit that only one Greek ever bothered to try exploring the world by boat - a Pytheas around 300 B.C. Pytheas even has an extant marble statue. It's in France though; not sure if they made one of their own or brought it to France from Greece(as they and many others did over the centuries).
Pytheas apparently discovered the tides. The tides are so slight in the Mediterranean, that nobody noted them. Pytheas voyages appear to be the last since the Phoenicians also made it out of the Med and into the Atlantic. It was also the last till the end of the medieval European period.
The Azores around 1427 were of course the first to be found. The major motivations of the Portuguese and Spanish for one wanted to go east by heading west was because of 1) the prices of goods from the East Asia market was through the expensive Byzantians and the 2) expensive Venitians. The net affect of this age of great wooden ships to explore the entire Earth for the first time was to leave the Venitians in the dustbins of history.
The idea of finding Asia by going west across the ocean actually goes back to Roger Bacon in 1249.
In 1487, Portuguese Bartholomeu Diaz set sail to find the end of Africa. He called it the "cape of storms." King Johnthe 2nd however didn't want future explorers from being dissuaded from trying again and again, so he called it the 'Cape of Good Hope'!
Christopher Columbus, in 1492, found of course the Americas. Yes, he didn't originally set foot on the mainland. But, that was just his first time finding land beyond the Atlantic ocean. He later did set foot on the mainlands, of South America anyways. He found, in 1498, a Orinoeo River, in what's now called Venezuela.
Vespucci and Martin Waldseemuller around 1507 recognized by descriptions of Asia and what Christopher Columbus was telling them, that it wasn't Asia he found but "the New world."
Vasca Da Gama found India in 1497. Francisco Corboda found Mexico in 1519. In 1523, Magellan circumnavigated the Earth. Magellan actually didn't make it. A fellow crewmember Juan Sebastian finished; he was in India or thereabouts when Magellan was killed; so, why turn back?! That's great rapid progress in such short time. The Magellan circumnavigation took three years. It took the recent Casinni spacecraft seven years to get to Saturn.
The Mississippi river was discovered in 1541 by Hernando de Soto. The Amazon was discovered in 1542 by Francisco de Orellana. The tribes were led by women; this reminded them of the Amazon women in Homeric epics, so they called it the Amazon river . . . !
The Portuguese and Spanish had found Asia and explored America by the 'southeast' passage. They practically owned it. So, the French, the English wanted to find a Northwest and Northeast passage. They of course ran into lots of ice. This started the great explorations of the North and South poles. William Buffin found Buffin bay in 1616 and came within 800 miles of the North pole. He first concluded there was no Northwest passage.
Here's an interesting tidbit. I had heard of Mauritius just a few months ago. I heard of it for the first time in my blogs stats; I got one hit a month or so ago from a Mauritius. I looked it up and found it was some small island near Madagascar(and Island on the east coast of Africa). Anyways, Mauritius was found in 1598. Some recent more significant tidbits I found last night while researching this latest blog entry was about a flightless bird. Apparently, because it knew no enemies, it would come straight up to the Dutch who first noted this island. The Dutch subsequently hunted it to extinction. Hence the birds name - the Dodo. People talk about the mass extinctions of today's industrial age. The mass extinction really happened back then at the great age of discovery!
The Columbus river was found in 1791; the Missouri river was discovered in 1804. Lewis and Clark was use both rivers to get from one side of the North American continent to the other.
Speaking of using rivers to get around which is kind of one reason I thought this was an important enough topic to wright up about Human history, the Nile river was not thouroughly explored to remarkably recent times!
Despite the Egyptians living there for thousands of years even before the classical Greeks civilization, none bothered to go back down and see the whole river! The Egyptians never made it much further than 1,500 miles of the rivers now known four thousand miles.
James Bruce around 1770 found two sources, the white and blue niles. He only explored blue nile into today's Sudan. If you look at a map of Africa, this doesn't seem far from Egypt, but then again, Africa is a big continent! Fact are, that the Egyptians certainly never conquered the Nubians. That might be one reason.
The white nile goes much further. John Speke and another guy who bailed out after awhile, found the source of the white nile. It's a lake, the second largest to Lake Superior - Lake Victoria. This was in 1862!
Here's a satellite image of Africa,
I know I've seen images of Africa many times; but, I never bothered to note the easily visible and hugh lake in middle eastern Africa! That's lake Victoria. A major point that I forgot to mention is that it took so long and so much more technological ability before Humanity discovered this.