Answer:
The correct order in which things happen in Twenty Thousand Legues Under Sea is the following:
- encountered a shoal of Argonauts
- passed through a milk sea visited the pearl bed and saw a giant pearl encountered a shark
- sailed through the Red Sea
- battled a giant dugong
- passed through a secret tunnel under the isthmus of Suez
- Ned plotted an escape
- Captain Nemo passed a box of ingots to a diver off Crete
- stop at Vigo Bay foiled the escape attempt
It was all perfectly lined with, with the exception of these two:
"battled a giant dugong" & "passed through a secret tunnel under the isthmus of Suez". The order in which it happens was swapped in the question.