The faith of the Israelites contrasts with the faith in false gods of the Egyptians, and we see that the waters overwhelmed the Egyptians. Can you imagine? The Egyptians must have been sincere in their belief, at least in their belief that they must obey Pharoah, whether or not they also believed in any other god before them. He was the leader, the commander of the army, and a descend of the gods. And truly, if this God of Slaves could split water, then their gods could hold it back, right?
Or perhaps the Egyptians looked and beheld a natural process that they had no doubt would endure? Recent years have seen a resurgence in explaining the miracle events of Scripture (and other religions) with a natural event. It's an attempt to address that the historicity of the events is likely, but to retain an anti-supernatural belief system. The Egyptians come to the Red Sea, (Reed Sea is also what the port of Solomon at Ezion-Geber was on, and it's on the Red Sea near Aqaba or Eilat) and the Red Sea has split. They've heard this can happen, and it's no big deal. There's no deity involved here, just a long wind, and shallow pool, right?
Either way, the Israelites are facing the biggest physical obstacle they've seen, and they are facing it fearfully hoping that God is on their side. That's another angle on this. Hebrews presents the Israelites as full of faith as they passed through. Go read Exodus 13-15. Are they really that excitied about this? No, they aren't. I'm seeing here that sometimes faith in action looks about like obedient desperation. Had the Lord God told Israel to do something else, like tunnel or turn and fight or build boats, I'm sure they would have preferred it. When you read the Exodus account, they didn't come and think, "Oh, no big deal, the sea will part." They were afraid. They had been obedient to this point, though not always with enthusiasm, and they were here, and trapped. They feared God had brought them out to die, and I hear the skepticism rising when they confront Moses.
You don't hear it? Did God bring us out here to die? Does God hate us? Did He really speak to you, Moses? Do you know what you're doing? Is God even real? After all, this seems like a horrendous plan to me!
Yet this was His plan. The Israelites went forward, probably more in fear and desperation than in anything else, and afterwards are remembered for their faith. It is not that we take on great goals in our obedience in hopes that we are remembered for our faith. It's that, whether out of fear or desperation, we obey God. We pass through the strangest of circumstances, and we are found, later, to have been faithful.
We find, at the end, that our trust was in the right place.