The seventh day of Pesach is a Yom Tov because on the seventh day of Yetzias Mitzrayim the miracle of the splitting of the Red Sea and the drowning of the Mitzriyim. Let us first analyze some pessukim in Beshalach concerning this miracle and parts of davening that also portray what happened on that special day.

a) (Shmos 14,31) וירא ישראל את היד הגדולה אשר עשה ה' במצרים וייראו העם את ה'

Yisrael saw the big hand of Hashem with which he did in Mitzrayim and they feared Hashem. Here we are after Kerias Yam Suf and the Torah is stating that Yisrael saw and acknowledged the powerful hand of Hashem in Mitzrayim which occurred seven days previously?

b) (Shmos 14,30) וירא ישראל את מצרים מת על שפת הים

Yisrael saw Mitzrayim dying (dead) on the seashore. It rather should have said the plural form Mitzryiim the Egyptians?

c) (Shmos 14,25) אנוסה מפני ישראל כי ה' נלחם להם במצרים

I will flee from Yisrael because Hashem has fought for them in Mitzrayim. Once again it sounds like they are referring to the Maakos. If so why does one have go back to miracles in Mitzrayim in order to realize that Hashem brought upon them the Maakos? Hashem demonstrated right here at the Kerias Yam Suf that He was fighting on behalf of Yisrael. ויהם את מחנה מצרים the clouds came down and turned the ground into mud which was then heated to a boil by the Pillar of Fire and the horse's feet were burnt and the wheels of their chariots fell off (Baal Haturim)?

d) The structure of the Shiras Hayam is אריח על גבי לבנה like brickwork and unusual large blank spaces between the pessukim. This is in contrast of Shiras Haazinu which are two columns opposite each other. מה נשתנה השירה הזאת מאחרות ? At first sight the two standing columns would seem more appropriate to Keriyas Yam Suf as Yisrael crossed between two pillars if water.

e) In Shacharis davening we say זדים טבעת וידידים העברת ויכסו מים צריהם אחד מהם לא נותר The willful sinners you drowned, the dear ones you brought across, and the waters covered their foes. Why are we mentioning the drowning of the Egyptians twice? Secondly, the order is wrong because first Hashem וידידים העברת and only laterזדים טבעת ?

f) At Maariv we say המעביר בניו בין גזרי ים סוף את רודפיהם ואת שונאיהם בתהומות טבע Who brought His children through the split parts of Yam Suf while those who pursued them and those who hated them He sank into the depths. It is obvious that the Egyptians who chased after Yisrael hated them deeply? Why two descriptions?

g) אשירה לה' כי גאה גאה I will sing to Hashem because He is exalted (above the arrogant) a double dose of exaltation. What is this phrase referring to?

(h) The Rambam writes that the mitzvah of סיפור יציאת מצרים at the night of the Seder is to retell the miracles that Hashem did to our fathers in Mitzrayim. The question arises that part of the Haggadah that we say in Maggid is all about the miracles that occurred at Kerias Yam Suf which were out of Mitzrayim. So according to the Rambam is seems that they should not be recited at the night of the Seder. That is why the Rambam does not have the Kerias Yam Suf miracles, in the nusach of his Haggadah. What is the opinion of the others which is our nusach that do say it as part of the סיפור?

The answer to all these questions starts with a Rashi that we brought earlier the passuk of כי ה' נלחם להם במצרים (c). Rashi writes במצרים, בארץ מצרים שכשם שאלו לוקים על הים כן לוקים אותם שנשארו במצרים that the same way that the Egyptians were being smitten at Yam Suf so too the remnant Egyptians in Mitzrayim were also smitten. According to Rashi the words ה' נלחם להם במצרים is not referring to the Ten Makkos but rather to a makka that happened to the Egyptians who remained in Mitzrayim simultaneously at the time of the splitting of the sea. This event was so traumatic that it brought fear into their hearts.

What makka was Rashi referring to? The Rokeach learns that before Hashem drowned the Mitzrayiim in the Yam Suf He made a tsunami to crash upon the remaining Egyptians in Mitzrayim drown them, and only then Hashem drowned the Egyptians who chased after Bnei Yisrael. Then Hashem shlepped the bodies of the Mitzryiim who drowned in the tsunami, back to Yam Suf. Upon seeing their fellow countrymen drowned, they said full of fear"I must flee for Hashem was fighting for Yisrael in Mitzrayim". It was then that Hashem drowned the Mitzrayim standing in the middle of the split sea.

With this interpretation of the Rokeach we can say that Rashi is of the same opinion and all our questions can now be answered. The Rokeach himself answers questions (e) that is says זדים טבעת וידידים העברת ויכסו מים . The mentioning of זדים before ידידים is because this is referring to the miracle tsunami that struck those remaining in Mitzrayim. Only afterwards the ידידים crossed, once again there was a second drowning for the Egyptians who chased Am Yisrael.

This will also answer why the Mitzriyiim were given two descriptions (f). The רודפיהם were those who chased after them into the sea. The שונאיהם are referring to the tsunami victims.

Even if one holds that the סיפור יציאת מצרים must contain only Eretz Mitzrayim contents (h), Kerias Yam Suf fits into this criteria because of the drowning of the Tsunami Egyptians in Eretz Mitzrayim.

The double lashon of כי גאה גאה (g) is the exaltation of the two drownings in two distant locations and yet Hashem mixed them together with the same water of Yam Suf.

The form of the Shiras Hayam (d) is writing phrases and large spaces. The writing segment symbolizes the miracle of the Egyptians whom we visibly saw their drowning as we stood on the shore. The empty spaces symbolize the drowning of the Tsunami Mitzriim whom we did not merit to see their deaths only their bodies which were emptied into the Yam Suf. We sing praise to Hashem for both salvations.

וירא ישראל את מצרים מת על שפת הים (b). The reason why the Torah did not write מצריים the plural form, because it wanted to include even the ones of the Tsunami people who died in Mitzrayim and came to the edge of the the Yam Suf.

The passuk says וירא ישראל את היד הגדולה אשר עשה ה' במצרים. This passuk is also referring to the Tsunami People. It doesn’t say to the Mitzriim but rather Mitzrayim. Hashem כביכול extended part of the Yam Suf to enter the land of Mitzrayim which is equivalent in size to the states of Texas and New Mexico, with which He drowned all the remaining males (see Rashi Yevamos 76b Biur HaGra Even Haezer 4:18). That is why it is called יד הגדולה a far reaching hand. The word גדול also means chesed. By ridding Mitzrayim of all its living males, Hashem did a great chesed and comfort for Am Yisrael that they should never think that the remnants of Mitzrayim will one day return to chase them again and take revenge or bring them back into slavery.