Lehi puts it this way:
6 Wherefore, I, Lehi, prophesy according to the workings of the Spirit which is in me, that there shall none come into this land save they shall be brought by the hand of the Lord.
7 Wherefore, this land is consecrated unto him whom he shall bring. And if it so be that they shall serve him according to the commandments which he hath given, it shall be a land of liberty unto them; wherefore, they shall never be brought down into captivity; if so, it shall be because of iniquity; for if iniquity shall abound cursed shall be the land for their sakes, but unto the righteous it shall be blessed forever. (2 Nephi 1)
It makes sense to me, then, that crossing the great waters is an apt symbol of establishing a new covenant with God.
Along these lines, I found a subtle connection with the Old Testament book of Lamentations:
What can I ·say [testify] about you, [L daughter] Jerusalem? What can I compare you to?What can I say you are like? How can I comfort you, ·Jerusalem [L virgin daughter Zion; C location of the Temple]?Your ·ruin [wound] is as ·deep [great] as the sea. ·No one [L Who…?] can heal you. (EXB, Lamentations 2:13)
This entire chapter mourns the loss of the covenant people, the temple, and God's protection. It's very sad to read.
Of note, this destruction took place shortly after Lehi and his family were safely guided away from Jerusalem.
Verse 10 of the same chapter is also noteworthy, as it sets up a preface for one of the major themes of the Book of Mormon. Notice the contrasting elements of this passage:
The elders of ·Jerusalem [L the daughter of Zion; C the location of the Temple] sit on the ground in silence.They throw dust on their heads and put on ·rough cloth [sackcloth; burlap; signs of grief or repentance].The young women of Jerusalem bow their heads to the ground [C in sorrow]. (Lamentations 2, Expanded Bible)
31 And , and arise from the dust, O Jerusalem; yea, and put on thy beautiful garments, O daughter of ; and thy and enlarge thy borders forever, that thou mayest be confounded, that the covenants of the Eternal Father which he hath made unto thee, O house of Israel, may be fulfilled. (Moroni 10)
(See also 2 Nephi 1:14, 21, 23 and 2 Nephi 8:24-25.)
Also compare this language from the title page:
The Book of Mormon highlights the theme of God remembering (and re-establishing) His covenant people in the latter days. Crossing the deep waters is one more way this is symbolically depicted. We'll close this post with a verse from Nephi's psalm:
EDIT: Not surprisingly, Stisa has already written on a related aspect of this symbolism in this post.
Which is to show unto the remnant of the house of Israel what great things the Lord hath done for their fathers; and that they may know the covenants of the Lord, that they are not cast off forever...
The Book of Mormon highlights the theme of God remembering (and re-establishing) His covenant people in the latter days. Crossing the deep waters is one more way this is symbolically depicted. We'll close this post with a verse from Nephi's psalm:
20 My God hath been my ; he hath led me through mine in the wilderness; and he hath preserved me upon the waters of the great deep. (2 Nephi 4)
EDIT: Not surprisingly, Stisa has already written on a related aspect of this symbolism in this post.