When the B’nei Yisroel were at the seashore, they served Hashem with mesirus nefesh, beyond their nature, making them worthy of kriyas Yam Suf.

When one serves Hashem according to his nature, Hashem leads him according to the rules of nature. But when one goes beyond his nature, Hashem reciprocates and performs miracles for him beyond the limitations of nature. 

~ R’ Michel of Zlotchev zt’l  (1726-1786)