Introduction
A river flows down the middle of the great street of New Jerusalem from the throne of God and the Lamb(Rev. 22:1). The tree of life, the same one that was once in the Garden of Eden, grows on both sides of the river(Rev. 22:2). The river is described as clear as crystal. We can have some clear water on Earth, but New Jerusalem will have water that is even clearer.
What direction does the river flow?
The book of Revelation doesn’t say which direction the river flows. The books of Zechariah and Ezekiel may have the answer as they likely describe Jerusalem in the Millennium reign of Christ. The Jerusalem in this period could very well mirror New Jerusalem on a smaller scale. Half the river flows east into the eastern sea or Dead Sea1 and the other half into the west into the western sea or Mediterranean Sea1(Zec. 14:8). When it enters what’s now the Dead Sea, the water becomes fresh2, meaning it provides life in areas that are barren.
How deep is it?
The book of Revelation doesn’t say how deep the river is, but Ezekiel might have the answer. At 1,500 feet(450 meters)3 from the source the river is ankle-deep(Eze. 47:3). At another 1,500 feet it is knee-deep(Eze. 47:4). At a third increment of 1,500 feet it is waist-deep(Eze. 47:4). At another 1,500 feet it is deep enough to swim in, yet no one could cross it(Eze. 47:5).
No more sea?
Is this a literal river? Some say it can’t be since Rev. 21:1 says New Earth will have no more sea(Rev. 21:1). Notice the verse says no more sea and not water. When the Apostle John wrote Revelation, the sea was something to be feared(footnote Steven J. Lawson, Heaven Help Us! (Colorado Springs, Colo.: NavPress, 1995), 108). The seas divided the nations, destroyed ships, were violent and resulted in lost lives. The river in New Jerusalem will not be anything like that.
Significance of water
Water is used metaphorically for eternal life in the Bible. Streams of living water are described as flowing from believers(John 7:38). Psa. 46:4 describes a river that makes the city of God a happy place. The verse describes the Holy Place where the Most High dwells. The book of Isaiah says we will have joy in drawing from the wells of salvation(Isa. 12:3), and God invites the thirsty to come to the waters at no cost(Isa. 55:1). Jesus talks to the Samaritan woman at the well about drinking from the water He offers so she will never be thirsty(John 4:13-14).
1 http://www.biblegateway.com/passage/?search=Zec.%2014:8&version=ESV
2 http://www.biblegateway.com/passage/?search=Eze.%2047:8&version=ESV
3 http://www.biblegateway.com/passage/?search=Eze.%2047:3&version=ESV