The second sentence is a kind of antithesis of the first sentence, which is often used in poetry, especially in seven-character quatrains and five-character quatrains. The long river faces the deep sea, and the tranquility barely corresponds to the settlement, but the steep Lego is somewhat unsmooth, so please ask the questioner to take out the whole poem and analyze it together. Understanding the second sentence alone means that in the deep sea, lonely cliffs stand there and enjoy themselves.