Sandy sinks to the shore silently is an example of what poetic device

Alliteration. alliteration is when the same sound is repeated at the beginning of multiple words in a sentence. in this case, it's an alliteration of S.

Alliteration.

Explanation:

Alliteration is a literary device used by writers in which a number of words that have the same consonant letter at the beginning of the words are repeated successively or in close association with each other. In the sentence "Sandy sinks to the shore silently", we have a series of words that began with the consonant "s", "Sandy, sinks, shore, silently". This is an example of alliteration.