3 days if you are vaccinated and departing in Seattle.
Effective April 1, 2022, pre-entry COVID-19 tests are no longer required for Fully Vaccinated travelers entering Canada by air, land (rail), or water (marine vessel). This means when a cruise ship enters one of Canada's ports, no COVID testing is required for fully vaccinated travelers (very limited exemptions). In this case entering Victoria, BC.
For pre-embarkation COVID-19 testing, since this cruise embarks/originates in the US (Seattle), you must use US CDC and cruise line requirements for negative COVID-19 testing prior to boarding.
(Canada's pre-embarkation testing requirements have no bearing here as you are embarking/originating your cruise in the US not Canada).
our testing requirements for cruises that embarks/originates in the US are in the Princess FAQs,