In Joshua 3, the Israelites cross the Jordan River on dry ground. God does this miracle to affirm before the Israelites that God is with Joshua, as God was with Moses.
But was it really a miracle? The Intervarsity Press Bible Background Commentary says the following about Joshua 3:16-17:
“3:16 parting of the Jordan. This is springtime (see 4:19), and the melting snow from the Anti-Lebanon mountains often creates a flood stage for the Jordan. Mudslides as a result of flood waters undercutting the cliffs or from seismic activity occasionally interfere with the flow of the Jordan at the very place mentioned here in the text (once as recently as 1927). Those recorded have generally blocked the Jordan for a couple of days.”
“3:17. on dry ground. There is an interesting inscription of Sargon II of Assyria (eighth century) where he claims that he led his army across the Tigris and Euphrates at flood stage as on dry ground.”
Maybe there was a natural cause for the “miracle” in Joshua 3. What’s important, in my opinion, is that the Israelites felt that they were experiencing God in that situation. After all, they were able to cross the Jordan right when they needed to cross it, which means that a natural event worked out in their favor. That doesn’t always happen in the world, and so it’s understandable that people feel grateful whenever it does.
I was one time talking about miracles with a couple of professors. They had problems with viewing miracles as a suspension of natural law. One of them defined a miracle as an event unusual enough that it raises a person’s consciousness of the divine (or something to that effect). I myself am reluctant to rule out the possibility that God breaks natural law at times, even though I understand why some deem that to be problematic: it strains credulity, and it raises the question of why God doesn’t break natural laws more often to alleviate pain, suffering, and death. But I’m also open to God working through nature rather than contrary to it.