Some people say that Israelites crossed the "Reed sea" and not the "Red sea". What is the right translation of the word "Yam Suph"?

The core of the question is to know whether the Israelites really miraculously passed through a parted sea or just some sort of marsh land.
When we look at the Biblical passage from Exodus 14, we get a clear idea of the kind of water body they passed through.
"Then Moses stretched out his hand over the sea, and the Lord drove the sea back by a strong east wind all night and made the sea dry land, and the waters were divided. 22 And the people of Israel went into the midst of the sea on dry ground, the waters being a wall to them on their right hand and on their left. " (Exodus 14:21-22).
We see that the waters stood on both sides as walls - and the Israelites passed through. That description isn't fitting for a marsh land or a shallow water body in anyways.
When we move down a bit more we see this - "So Moses stretched out his hand over the sea, and the sea returned to its normal course when the morning appeared. And as the Egyptians fled into it, the Lord threw the Egyptians into the midst of the sea. 28 The waters returned and covered the chariots and the horsemen; of all the host of Pharaoh that had followed them into the sea, not one of them remained." (Exodus 14:27,28).
Well, this description certainly doesn't allow the possibility of the water body being some sort of marsh land or shallow water. If it were, it would be absurd to think that a whole army was drowned because of it! So when we see the description by the author, we see that he was talking about a water body that could stand like walls on both sides(when it was parted) and could drown a while army(when it returned to the normal state).