Rhythmically, an anapest is a foot which consists of two short, unstressed syllables followed by a final stressed syllable. A good way of remembering this is to say the word "anapest" out loud, as it mimics the rhythm of an anapest itself with its two short syllables of "ana" followed by the stressed syllable of "pest." Reading this poem reveals therefore that the metre of the poem does vary, but extensive use of anapestic rhythm is made in order to enact the relentless sound of the crashing of waves that is referred to in the first line of the poem and also expresses the tumult of emotions that the speaker is experiencing. Strict anapestic patterns can be found in the following lines:
That he shouts with his sister at play
That he sings in his boat on the bay!
And the sound of a voice that is still!
This is an excellent poem to analyse and to think about the way that a poem's rhythm can be so powerful in terms of its impact, and also to demonstrate how poetry is meant to be read out loud and listened to rather than just read on a page.