I looked out of my window in the dark
At waves with diamond quills and combs of light
That arched their mackerel-backs and smacked the sand
In the moon's drench, that straight enormous glaze,
And ships far off asleep, and Harbour-buoys
Tossing their fireballs wearily each to each,
And tried to hear your voice, but all I heard
The reflection of the moon shining on the ocean creates a straight line – ‘a straight enormous glaze’ – and the idea of ‘drenching’ connects with the weight of water throughout the poem: 

Extract from Five Bells