They said to Joshua, Truly Yahweh has delivered into our hands all the land; and moreover all the inhabitants of the land do melt away before us.
"The fords of the Jordan," mentioned back in  Joshua 2:7, does not mean that adequate passage for a nation like Israel was located there.  It is even doubtful that the spies were able to use them, due to the flood-stage of the river.  Many commentators have expressed the opinion that the spies "swam the river," both coming into Jericho, and after leaving it.  The Septuagint (LXX), also, seems to indicate the same thing, due to their mention of the spies as "young men," who would have been able to do such a thing.