Mitzrayim was smitten with Ten Plagues which terminated with Maakas Bechoros. The question that should bother all of us why isn’t the drowning of the Egyptians at Yam Suf counted as an eleventh smite? To reinforce the question let us examine the passuk (Shmos 11,9) לא ישמע אליכם פרעה למען רבות מופתי בארץ מצרים.  Pharaoh will not listen to you in order that I shall increase my wonders in the land of Egypt. This statement was said to Moshe after informing him of the upcoming plague of Maakas Bechoros. If so, what other “wonders” (said in the plural form) will Hashem perform in Mitzrayim besides Maakas Bechoros that the plural lashon of מופתי was used?
The Ramban interprets the plural “wonders” to refer to Maakas Bechoros which included multiple wonders such as destroying the idols and killing the first born of their animals as well. Rashi however interprets the plural form to include the future wonder of Kerias Yam Suf in which the Egyptians also perished. The Meforshim explain Rashi’s interpretation that these words רבות מופתי includes specifically three other miracles. They are derived from the lashon in the passuk  that מפתי  is plural which means at least two, and רבות includes one more. All together three events are to follow the 9thmaakah which are מכות בכורות קריעת ים סוף, וינער בים. According to Rashi it appears that קריעת ים סוף  and וינער are included in the word מופת  just like מכת בכורות . The question therefore arises why is there not at least eleven Maakos since they are both called מופת?
In order to answer this we have to go back to the beginning of creation and the sin of Adam Harishon. Adam can be compared to the Bechor of the human race. When he transgressed Hashem’s command he was dwarfed from his spiritual stature and dimensions. He was a smitten man, because now it was easy to become enslaved to his yetzer harah. After his falling, there followed two other events that compromised Man’s stature even further. The first was the Flood and the second was the generation of Haflagah who built the Tower of Bavel. The Pachad Yitzchak ztl explains the parameters as follows that varying degrees of punishment were delivered to those who sinned before Him, however, diminishing the stature of Man for his rebellion against Hashem has terminated after these two events.
Man is elevated to the highest category called Medaibar, a creation that alone possesses the unique gift of speech. As the passuk states in the creation of Adam ויהי אדם לנפש חיה and the Targum interprets this to mean לרוח ממללא a spirit that  speaks. Speech is a result of the combination of a soul and a body. As long as the body subjugates itself to the neshama, then Man merits to be called a Medabair the creation of G-dliness who mirrors Hashem who created the world with life energy through the power of speech ויאמר אלהים יהי אור etc. However, If the soul of Man becomes subservient to one’s body, this creative life force of Man symbolized by speech becomes defective and distorted. Man then falls short of emulating Hashem and thereby falsifies his title ofאדם  which is derived from the lashonאדמה  (ahdameh) I will make myself similar  (דומה to Hashem).
After the sin Adam hides from Hashem. When confronted by Hashem on the reason of his hiding Adam answers את קולך שמעתי בגן ואירא. Your voice I heard in the Garden and I was afraid because I was naked. This could be interpreted to mean as follows. Hashem’s voice is this creative life force and energy. That is why every object of creation can be called דבר, a thing, from the lashon of דיבור since it was brought into existence from the dibbur of Hashem. Before the chait, Adam was able to hear the קול ה’ which was the dibbur of Hashem in every davar. However, after the chait Adam realized that this sensitive power of hearing Hashem’s dibbur in every creation was compromised and no more naturally attainable. This is hinted in the words of Adam את קולך שמעתי בגן Your voice Hashem of the creative power of your speech “I heard”, in the past tense. However, now after the chait it is no longer automatically audible. Therefore I was filled with fear after realizing that I lost and I became naked of my former lofty dimension possessing a sensitive natural radar to pick up the frequency of Your kol Hashem residing in every molecule of creation.
Interestingly, the two further fallings of Man’s dimensions during the Flood and Haflaga also hint to Man’s compromising of his dibbur. The measurements of the Taiva were ש three hundred amos length, ן fifty amos width, and ל thirty amos height which spellלשן  language. Also the Ark is called תבה which also means word. Noach was the only one who was saved with his family for only he preserved the title אדם and the power of healthy speech which can only exist when the neshama rules over the body.
Before the Tower of Bavel was built, all civilization spoke only LashonHakodesh (Bereishis 11,1 Rashi). After the chait and the halting of building the tower, the singular language was split into seventy languages corresponding to the seventy nations of the world. Rav Hutner ztl described this deliberate intervention of Hashem causing man to speak multiple languages in a deep way, as the ripping of Man the Medabair into seventy fragmented parts. The צורת האדם was again diminished.
In order for the Second Edition of Man Am Yisrael to reconstruct the original stature of Adam Harishon there was the necessity to rectify not only the chait of Aitz Hadaas but also its two compromising extensions during the period of the Flood and the Haflagah.

Galus Mitzrayim was the root of all four galiyos. Every galus is an extension and ripple effect of the chait of Aitz Hadaas (Sfas Emes וארא תרנג). Therefore Yetzias Mitzrayim was a tikkun for the chait of Aitz Hadaas. For this reason we find many similarities between the AitzHadaas and the geulah from Mitzrayim. The goal of the nine Maakos was the lead up to the tenth plague of Makas Bechoros smiting the ראשית root koach of tumah of Mitzrayim. With the fall of the ראשית של טומאה Am Yisrael emerged as בני בכרי ישראל – the ראשית  of kedusha. The Ari Hakadosh writes that during AmYisrael’s bondage to Mitzrayim their dibbur was in galus and was compromised. This parallels the compromised dibbur of AdamHarishon after the eating from the AitzHadaas. That is why he could no longer naturally hear the dibbur of Hashem contained in all created matter. This is the very reason why the geulah is expressed in the name of the YomTov פסח which is composed of two words פה סח the mouth speaks which means the dibbur of Yisrael exited the galus.
On the night of the Seder theקול  of the Egyptians were screams and wailing over the deaths of their bechorim. In contrast, there was the presence in the houses of the Yidden the קול of Hallel and praise to Hashem which is a demonstration of tikkun hadibur where neshama reigns over the body.
Just as the chait of Aitz Hadaas came about through eating so too the geulah from Mitzrayim came about with the eating of the KorbanPesach.  At the Seder we are commanded to eat matzos made of wheat to allude to the opinion that the Aitz Hadaas was a wheat tree and the night of the Seder there was a tikkun. We are commanded at the Seder to drink four cups of wine to allude to the tikkun of the Aitz Hadaas which according to another opinion was the juice squeezed from its grapes. Just like after the eating from the AitzHadaas the Shechinah departed from Adam (Bamidbar Rabba 12,6), the opposite happened during Maakas Bechoros, that Hashem Himself descended to Mitzrayim to kill the Egyptian first born and to save the bechorim of Yisrael.

After the tikkun of Adam Harishon from the first chait of Aitz HadaasAm Yisrael had to rectify the two extensions of the AitzHadaas which were Mabul and Haflagah. The miracle KeriasYamSuf corresponds to the fixing of the Haflagah. As we explained above the sudden change going from one language to seventy with no one understanding what the other person was saying was tantamount to ripping the Adam into strips. So too Kerias YamSuf was split into strips as the passuk says לגוזר ים סוף לגזרים. An allusion to the connection between the two episodes is found in the gematriahים לגזרים equals דור ההפלגה with the two words.
The punishment of the Egyptians drowning in YamSuf came in the form of וינער as Rashi describes like a man who stirs a pot of food and turns the upper contents of the pot downward and the lower contents upward. The Egyptians would rise and descend and be smashed in the sea. This method of death was a tikkun for the generation of the Flood – מבול which means everything was mixed up (Rashi 6,17 that is why Bavel is called  (שנער שננערו שם כל מתי מבול)
Now we can understand Rashi’s interpretation above. Hashem includes in the words רבות מופתי the teaching that we learn from here three additional events to the nine maakos already brought upon Mitzrayim which are מכת בכורות קריעת ים סוף וינער . We asked that if we learn the first two events from the word מופתי which is in plural form, then וינער should be counted as an eleventh maakah to Egypt. We will now answer that Rashi learns from a different origin these additional three events. From the word מופתי Rashi learns only Makas Bechoros like the Ramban. Rashi learns from the wordרבות  the two extensions of Yetzias Mitzrayim which are Kerias Yam Suf and the stirring of Mitzrayim in the sea. An allusion to this explanation is in the gematria ofרבות  which adds up to דר מבול דר הפלגה. That the miracles that occurred at KeriasYamSuf, the splitting of the sea, and the drowning of the Egyptians, corresponded to the two extensions of the chaitAitzHadaas. Since they are only extensions רבות)) from the root of MaakasBechoros מופתי)) which is the tikkun of the ChaitAitzHadaas in its source, the maakah of וינער drowning the Egyptians is omitted from the count of the maakos after the tenth maakah of מכת בכורות.  
In the nusach of the BirkasGeulah of Shacharis, this explanation of this group of three becomes more evident. כל בכורי מצרים הרגת ובכרך גאלת  וים סוף בקעת וזדים טבעת וידידים העברת. Apparently the list of events is out of order for after the splitting of the sea, AmYisrael crossed and then the Egyptians perished? One can answer that even though it is out of order, nevertheless, is was set in this seder to connect the three events together, that of the killing of the bechorMitzrayim, splitting of the sea, and the death of the Egyptian through וינער. This was in order to demonstrate that together they served a tikkun for the Aitz Hadaas and its two ripple effects of the Mabbul and Haflagah.

– Rav Brazil
Gut Shabbos