A combination of high-pressure mist and crew members with hoses extinguished the fire, Kyle Moore, spokesman for the Seattle Fire Department, told the paper. The city dispatched a fireboat, and a few units to the Pier 91 cruise terminal, as a precaution.
Holland America brought the ship back "out of an abundance of caution and in cooperation with the U.S. Coast Guard," a company statement said.
No evacuations were needed, firefighters reported.
The Westerdam was beginning a 7-day Alaska cruise with 2,086 passengers and 798 crew members onboard when the blaze occurred.