The water imagery suggests that the protagonist goes through a baptism.
The text of a novel is more explanatory with details and the setting. In the movie version of novels, the movie is just flowing which makes it almost seem to be shorter. As to the text of a novel it's said\explained when a noise is made or when somebody walks in or by. In my opinion, although it would take more dedicated time to read the text of a novel first and the movie second it would give the reader's and viewer's a better understanding of what is being watched in the movie version.
I believe Dante’s universe is orderly in a way that punishment for sins corresponds to the actual sinful act. What these sinners did to other in life,they expected themselves in death. Hope this helps