Read the poem. seacoast silhouette how does the alliteration in line 6 affect the poem's tone?

It gives the poem a peaceful mood.

Explanation:

An alliteration is a kind of repetition based on the same sound at the beginning of a series of words that are close to each other. In the poem, the mentioned line is "silent and somber and still," and the title itself is another one as we can see in "Seacoast Silhouette."

The poem describes how the moon is reflected in the water and that is the object being described in line 6, since line 5 is "But the moon above is a statue," and it has an effect on how the observer perceives the moon and the whole context, meaning that it is calm and peaceful.