1)
What is the significance of making the water stand?
1.
Malbim: This enticed the Egyptians to descend into the water, for it stood like a pile - "Ne'ermu Mayim" (Shemos 15:8). This was due to Hashem's Midos, to drown them Midah k'Neged Midah - "Ki va'Davar Asher Zadu Aleihem" (Shemos 18:11).
2)
What is "Kemo Ned"?
1.
Rashi: It is a tall mound. The Targum of "Nitzvu Chemo Ned" (Shemos 15:8) is 'Kamu ch'Shor.' Radak - the water was like a wall for them (Shemos 14:29).
