Things definitely take a turn for the worse after the Mariner kills the bird. Really, if the albatross had not come along these guys would have frozen to death. Freezing to death however would have been infinitely more pleasurable than what happened after the Mariner kills the great bird. One of the fist signs killing the albatross was a stupid thing to do was that the wind stops and the ocean turning to slime.This casts a rather dreary tone and mood. Things just get worse from there. There is a ghost ship and that's kind of cool. The worst of it is that they have no water hence the famous quote, "Water, water, every where,: Nor any drop to drink". Then things go downhill,
With throats unslaked, with black lips baked,
We could nor laugh nor wail;
Through utter drouth all dumb we stood!
I bit my arm, I sucked the blood,
And cried, A sail! a sail!
With throats unslaked, with black lips baked,
Agape they heard me call:
Gramercy! they for joy did grin,
And all at once their breath drew in,
As they were drinking all. (III)
Can you see the switch in tone? This is all because the Mariner killed that damned bird! Things don't get better until the Mariner discovers his inner nature's child but that comes much later.