10 And a river went out of Eden to water the garden; and from thence it was parted, and became into four heads.
11 The name of the first is Pison: that is it which compasseth the whole land of Havilah, where there is gold;
12 And the gold of that land is good: there is bdellium and the onyx stone.
13 And the name of the second river is Gihon: the same is it that compasseth the whole land of Ethiopia.
14 And the name of the third river is Hiddekel: that is it which goeth toward the east of Assyria. And the fourth river is Euphrates.
One of the things we need to remember is that after the flood, a lot of the known world was displaced. We can assume where these rivers were located, but the truth is that much of the terrain on earth was totally changed after the flood.
But, HERE is an interesting documentary about the four rivers:
(Remember that all of this is speculation, and that this is for thought purposes only)