Thank you for suggesting me a website on audiobooks. Here are some sentences I'm not sure of.
1) Dr. Frankenstein can be seen as Rousseau's primitive man, detached from society and unspoilt by civilization.
2)He can also be seen as the dark side of Victor's personality, that wants to exceed human limits. The monster, indeed (instead?), as a crime against nature.
3)The ship was cheered and it travelled southward to reach the equator. Then a storm carried the mariner out of line, to the South pole. There was (or it was) a huge storm that chased them like a bird.
4)The sea was as green as emerald and the ice that was surrounded the ship, roared and cracked like a giant monstern (?).
5)Then an albatross appeared through the fog which seemed to represent a Christian soul (better: which was greeted as if it were a Christian soul). It lead them for nine nights.
6)They were into a tempest with rain and snow (better: they were caught in a tempest).
1 - OK
2 - I'd use "indeed" and replace "as" with "is".
3 - What does "cheered" in the first sentence mean to you?
Instead of "out of line" in the second sentence, you need "off course".
Keep "There was" in the third sentence.
4 --> The sea was as green as emeralds, and the ice that surrounded the ship roared and cracked like a great monster.
(Read carefully to pick up all changes, including punctuation changes.)
5 - Delete the words in parentheses. Replace "lead" with "led" since it's past tense.
6 - Yes, "they were caught in a tempest" is better.