When Am Yisrael stood at the foot of the Yam Suf, Hashem commanded us to start traveling, even before He commanded Moshe Rabbeinu to split it.  The commentators explain that we had to go so far out into the sea that the water went up to our noses – only then did the sea actually split.

From this, we learn that Hashem usually performs miracles for us only after we have done everything we can do to help ourselves.  ~ R’ Shlomo Brodt