Canto III: I, the West Wind, the Mediterranean Sea
Thou who didst waken from his summer dreams The blue Mediterranean, where he lay, Lulled by the coil of his chrystalline streams,
Beside a pumice isle in Baiæ's bay,
The speaker tells us more about the West Wind’s wacky exploits: the Mediterranean Sea has lain calm and still during the summer, almost as though on vacation "beside a pumice isle in Baiæ’s bay," a holiday spot for the ancient Romans. But the West Wind has woken the Mediterranean, presumably by stirring him up and making the sea choppy and storm-tossed.
The Mediterranean is personified here as male.
And saw in sleep old palaces and towers Quivering within the wave's intenser day,
All overgrown with azure moss, and flowers So sweet, the sense faints picturing them!
During his summertime drowsiness, the Mediterranean has seen in his dreams the "old palaces and towers" along Baiæ’s bay, places that are now overgrown with plants so that they have become heartbreakingly picturesque.
Thou For whose path the Atlantic's level powers
Cleave themselves into chasms, while far below
The speaker claims that the "level" Atlantic Ocean breaks itself into "chasms" for the West Wind.
This is a poetic way of saying the wind disturbs the water, making waves, but it also suggests that the ocean is subservient to the West Wind’s amazing powers.
Cleave themselves into chasms, while far below The sea-blooms and the oozy woods which wear The sapless foliage of the ocean, know
Thy voice, and suddenly grow grey with fear, And tremble and despoil themselves: O hear!
In the depths of the Atlantic Ocean, the different kinds of marine plants hear the West Wind high above and "suddenly grow gray with fear" and thrash around, harming themselves in the process.
Once again, the speaker ends all these descriptions of the West Wind by asking it to "hear" him.