The poem has a very simple concept. It focuses on one eagle alone in the wild. In the first line, the eagle is atop a mountain, poised to strike. He is high up where no other animal or human can go. He is alone in his grandeur, with the sun and the bright blue sky forming the perfect background scenery.
The second stanza shows the only action of the eagle. The first and second line show that as he watches from his high perch, the sea moves below him. Then, in the final line, the eagle makes a grand dive towards the sea. The poem ends here, with the reader not quite sure why the eagle dived off his mountain roost.