Query set to be defined (open issue)
Which ships crossed (polluted!) area A at least once ?
Which ships were within area A during time interval T ?
Which ships were not further than 10 miles from area A during time interval T ?
How many ships stayed within area A more than two weeks ?
What was the two week period when area A was the most crowed by ships ?
How long ships S1 and S2 have been not further than 1 mile one to the other ?
Etc.. (these are only suggestions...)