Proper documents for non-Canadian citizens who are residents?

Question

I need to find out what sort of documents my friends need. They are citizens of Germany (German passports) but reside in Canada. They would like to take a cruise that departs from the United States. What specific travel documents will they need?

Answer 1

they will need to travel on their German passport, and carry their permanent resident card to prove Canadian residency

Answer 2

They don't need any additional documentation apart from their passports and their Canadian visas/permanent resident cards. If the cruise is visiting a country other than the US, they should check to make sure that the country they are visiting does not require a visa.