How does Coleridge show the pain, the suffering and the repentance in "The Rime of the Ancient Mariner"?

The Mariner's pain is shown in the punishment he receives. He not only feels remorse and guilt over his own senseless actions, but it forced to watch the pain and suffering of his shipmates, as they die one by one, until no one is left. His guilt is thus doubled, and the pain of that guilt follows him for the rest of his life. The Mariner is further punished through his inablity to pray, to communicate with God and ask forgiveness, and absolution from the priest doesn't give him solace. Thus, he relives his experience and pays penance, each and everytime he realtes the story.