On the understanding that “[…] with God all things are possible” (Mat 19:26), it doesn’t seem that the Creator chose to perform that miracle (the separation of the Red Sea waters) in a instantaneous manner. Later on, we will see the biblical grounds for this conclusion.
To reach a more complete view of this happening is necessary that we collate the ‘prose’ passage of Exo 14:21, along with the ‘poetic’ passages of Exo 15:8 e Psa 18:15-16 (quoted in some BH answers to this question).
Exo 14:21 is almost a ‘technical’ description of the God’s manner to separate the waters. Indeed, the phrase ‘by a strong east wind all night’ (ברוח קדים עזה כל הלילה) reveals the manner in which God chose to perform that salvation, namely, through the aimed control of some of the universe‘s physical forces, guiding them (יולך, literally ‘causing them to go, to walk’) to perform a special, extraordinary (= out of the ordinary) ‘task’, that is, allowing the people of Israel – devoid of any vessels - to cross, unharmed, a sea channel. The precisation “all night” (כל הלילה) confirms a progressive (not instantaneous) action, in which God forced a very huge wind (רוח]…[ עזה]]) to do so. Note that this term (רוח) indicates an ‘invisible moving force’, so it can aptly be translated also ‘spirit’, as in Gen 1:2 [interestingly, the English term ‘spirit’ comes from the Latin verb ‘spiro’, namely, ‘to blow’, 'to breath']).
That wind (רוח) was to blow in a specific direction (from קדים, ‘East’, according the Bible), in a specific angle (as respect the horizontal walking surface), and with a specific duration (a night), so to create a passage enough wide to permit all the Israelites to cross, in one night, the Red Sea channel.
What else we may understand by the ‘poetic’ passages of Exo 15:8 e Psa 18:15-16?
In the first place, Exo 15:8 spoke about a רוח, the same term used in Exo 14:21, that there is translated ‘wind’ (by the far majority of Bible translations). Instead, here in Exo 15:8 the majority of the translations opt for the term ‘blast’, so thay may sum – in an a single term – the two concept of ‘powerful, strong‘ and ‘wind’.
In second place, the inspired text uses the figure of speech of anthropomorphism when it speaks about the ‘nostrils’ (ap) of God (sorry, it is incorrect to say that the inspired writer used the figure of speech of hyperbole, whatever the Interpreter’s Bible says, since this latter term possesses a very different meaning and linguistic aim). A similar figure of speech was utilized by Lord Jesus, paralleling the whiff of his mouth with the holy spirit ‘filling’ in the apostles (Joh 20:22) [as in Hebrew, in Greek, too, the term pneuma (utilized there) can carry the two meanings of ‘(physical) wind’ and ‘spirit’].
Finally, consider now some aspects of Psa 18:15-16.
Above the fact that the verse 15 utilizes the same phrase of Exo 15:8 (about the ‘breath of Your nostrils’), almost shockingly, that powerful operation of God, did permit the Israelites to see the bottom of the sea channel(s) (אפיקי) before they crossed it: what a unique spectacle!
The poetic character of this passage is enhanced also by the beautiful use of parallelism, that equalized the ‘sea channels’ (אפיקי) – in this instance, the bottom of the sea channel - with the ‘foundations of the (earthly) world’ (מוסדות תבל).
Conclusion
Were the waters parted instantly? The (micro- and macro-) Bible context indicates that God chose to perform a progressive (non simultaneous) action.
The utilization of some figure of speeech in the related passages of Exo 15:8 and Psa 18:15-16 do not hinder this conclusion, but add an emotional involvement to the strictly historical account.
What a manifestation of power and love, from God’s part, for the sake of his people Israel!
