ולא קרע לנו את הים דיינו שיוכל להצילנו ונלך לדרכנו. ולא העבירנו בתוכו בחרבה אלא במעט מים או במעט טיט אך הם הלכו ביבש' בתוך הים.
Abudarham on the Haggadah
In order to save us from the Egyptians, it would have been enough that the sea split and we trudged through the mud and silt that naturally covers the sea bottom. To show His love for His people, G‑d performed an additional miracle, making our path as dry and firm as land that has never been covered by water.
Based on the teachings of the Lubavitcher Rebbe, Courtesy of MeaningfulLife.com
In his Tanya, Rabbi Schneur Zalman of Liadi describes three spiritual personalities: the rasha (sinner), the tzaddik (perfectly righteous person) and the beinoni (the intermediate). The rasha is one whose revealed life — his deeds, speech and conscious thoughts — is at odds with his hidden essence. His soul is "literally a part of G‑d above" no less than the most perfect of his brethren; but his daily life includes acts that are a transgression of the divine will. His quintessential desire is to be faithful to his Source, but he consciously desires things that impede his relationship with G‑d.
In the tzaddik, there is perfect harmony between the hidden and revealed portions of his self. His intrinsic love of G‑d spills over into his revealed life, so that he desires only that which enhances his bond with the Almighty and is repelled by anything that threatens it. He is one who has "transformed his sea into dry land" — whose quintessential self and manifest self are one and the same. Between the rasha and the tzaddik is the beinoni, the intermediate.
Like the rasha, the beinoni desires evil; but he never allows his negative impulses to find expression in action, speech, or willful thought. In other words, the beinoni is a behavioral tzaddik and a psychological rasha. On the behavioral level, his life is in complete conformity with his inner identity as a spark of the divine torch.
Psychologically, the dissonance between his essence and his conscious self remains. The beinoni is one who has split his sea, but who still struggles along its muddy bottom. He has penetrated his hidden self enough to get across to the other side. He gets the same results as the tzaddik: his daily life is a perfect reflection of his innermost self. But his sea has not been transformed into dry land. Life, for the beinoni, is a constant struggle with the contradiction between sea and land.