As demonstrated in these verses, family members are not to give up on one another. Nephi did not give up on his wayward brothers. He encouraged them “with all the energies of [his] soul,” continually clarifying the teachings of his father.
The river of water represents the filthiness of the world, but Lehi was so “swallowed up” or so preoccupied with better things that he didn’t particularly notice how filthy the water was. Later, we encounter missionaries who were so “swallowed up” in the joy of Christ that they didn’t notice the depth of their own afflictions and deprivations (Alma 31:38). It is good to be “swallowed up,” or caught up, in the things of God.