The Israelites crossed the Jordan when the river was at its widest, deepest, and swiftest, in late April or early May. As the snow on Mt. Hermon melts and the rainy season ends, the Jordan rises to a depth of10-12feet and floods to a width of300-360 feet at this point today. Normally it is only150-180 feet wide here. However, in Joshua"s day the river may only have been full up to its banks, as the Hebrew text suggests. The people considered crossing the river at this time of year by swimming a heroic feat in ancient times (cf. 1 Chronicles 12:15). This is probably how the spies crossed. [source][source][source]
The town of Adam ( Joshua 3:16) stood about18 miles north of Jericho near where the Jabbok River empties into the Jordan Valley. Interestingly, several earthquakes have sent much soil into the Jordan River in modern times at this very location, damming up the river for many hours (in A.D1267 , 1837 , and1927). [1] Perhaps an earthquake is what God used in Joshua"s day too. God may have supernaturally used a natural phenomenon, a landslide, near Adam to cut the waters of the Jordan off as they flowed south. [1] Another possibility is that the phenomenon was completely supernatural. [3][source]
Two million Israelites could have crossed the river in half a day if the procession was a mile or more wide. The dry ground ( Joshua 3:17) was a miracle too (cf. Exodus 14:21). [source][source][source]
The major emphasis in chapter3is on the great miracle that God performed to lead the Israelites into the land. The conquest of the land would continue God"s works for His people, all of which they were to remember and appreciate. [source][source][source]
"The people of God [4] must realize that God does not help them automatically. God helps them when they obey his commands given through his leader." [5][source]