Salvēte, amīcī!
In that chapter, the following reads:
“Rēx quoque Aegyptius, Hebraeōs gradientēs īnsecūtus, nōn dubitāvit mare, quā patēbat, ingredī cum ūniversō exercitū.”
The marginalia say quā in a synonym for quā viā, ubi, but unless patēre has a meaning other than to not be hidden and to be open which I forgot or do not know, it does not seem to make sense to say that the Pharaoh and his army stood exposed in the open sea (as he had not entered it yet). I thought that patēbat might be a typo for patēbant agreeing with Hebraeī, in which case the sentence would make perfect sense: The Pharaoh entered the open sea, where the Hebrews were exposed.
By the way, can patēre mean to be exposed without protection (like an abandoned child)? So far I have only found it meaning to be open and to be easily seen, obvious.
Bene valēte,
Joannēs.