Additionally, it is stated there in Pirkei DeRabbi Eliezer: "Rabbi Eliezer says, on the day the waters were gathered, on that very day they froze and became twelve paths, corresponding to the twelve tribes, and they became walls of water, and between each path there were windows, and they could see each other." The reason for this, as we have explained, is that the splitting of the Red Sea was due to the unity and cohesion that existed among them, as one person with one heart. Therefore, Hashem made it so they could see each other and rejoice in each other's salvation, which is the ultimate purpose of unity.