As his story begins, the Mariner's ship enters icy waters. There, he unthinkingly shoots the innocent and helpful Albatross with his cross-bow, killing it. The mariner does this because he can. He doesn't value the Albatross, think about God, or regard the bird as a creature formed by God.
As a result, the Mariner and the rest of the crew are punished harshly for this transgression. However, in the midst of his suffering, the Mariner glimpses the beautiful motion and color of water snakes. They seem to shine as they coil and swim, flashing colors such as blue and green. The Mariner recalls that:
A spring of love gushed from my heart,
And I blessed them unaware
Because of this spontaneous overflow of emotion, the Mariner is freed to pray. The dead Albatross falls from around his neck and into the sea. The Mariner is finally able to sleep. When he awakens, it rains, and he and the crew can finally drink. Finally, too, after being stranded so long, the ship is blown back on course by the wind. The curse has been lifted, and the spell has been "snapt."
As the Mariner tells the Wedding Guest, he has learned that it is good to go to the church ("kirk") in the community with other people and pray. He has discovered that:
He prayeth best, who loveth best
All things both great and small;
For the dear God who loveth us,
He made and loveth all.
The Ancient Mariner has discovered the importance of loving and respecting all of God's creation.