Denotative analysis:
The wedding-guest is frightened by the Mariner's story and is afraid the old man is a spirit or a dead man, but the sailor assures he didn't die like his sail-mates, contrarywise  he was the only one to survive on the ship. 
The Mariner describes his agony on the wide sea to the Wedding-Guest: he was so accustomed to the landscape of the sea and the sky that he could see it even when he closed his eyes, and he complains no one took pity on his soul; for seven days and seven nights he watches the journeys of the moon and the stars.

All of his attempts to say a prayer did not work as he looked to the open eyes of the dead men of the ship who - in hias opinion  - were sending him a curse.

Lastly, when he saw same water-snakes, same God-creatures, and he became aware of  their beauty and will to live, he unconsciously blessed them, and ON  that moment the albatross tied at his neck FELL into  the sea and set him free.