Check out this description of various tidal wetlands:
http://www.dec.ny.gov/lands/5120.html
You'll notice some have a maximum of one foot of water at low tide while another type (2020 LZ) can have an average of 6 feet at low tide. Given the range of different depths for tidal wetlands, it is quite plausible that an army, chasing fleeing Israelites, would start across wetlands. Travel would be difficult and as the water rises around them, they would turn back to flee. Unfortunately, at that point, it might be too late. Horses would fall, trapping their riders, chariots would break, and even those that could swim might find their legs sinking into mud, trapping them in growing waters and drowning them all.
The literal story has the Egyptians walk between two walls of water through a sea (an act of magic), acknowledge that the Lord fights for the Israelites when their chariot wheels get caught in mud (a mundane act), and then try to flee.
Which is more sensible: 1) an army chases Israelites too far into a tidal marshland and are caught by the incoming tide before they can escape or 2) an army fails to recognize the power of the Lord is behind the parting of a sea, chases Israelites into the channel, and then realizes that their chariot wheels being caught in the mud is caused not by the natural properties of mud, but by the power of the Lord they failed to recognize was causing the sea to part, causing them to finally try to turn and flee.